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U.S./Canada Edilion:
Inlernationai Edition:

$2.50
$2.95

rEBRUARY 1983 -^^^ ^i^fl/f^^^.i^^' united Kingdom Edition: £2^00

Advancing Computer Knowledge

PET Vet: Commodore 64's Super Sound

FIRST THINGS FIRST.
LEARN ALL ABOUT P

When you don't know the first thing about your new
Apple 11* you need a friendly, cheerful, easy going teacher at
your side. And the ELEMENTARY APPLE is just that kind of
book.

It sweeps away the confusion— explains your Apple in
everyday language — shows you how to hook it up, how to use
the keyboard and work on the screen.

Gently and carefully it gives you an understanding of all
the things your Apple can do. And then, it even shows how
easy it is for anyone to write a simple program— provides
common sense answers about graphics, utility programs, and
the how and why of word processors, business programs and
hardware like printers.

VISA/MASTERCARD accepted. $2.00 shipping/handling charge.
(California residents add 6'/4% sales tax)
•Apple II is a trademark of Apple Computers, Inc.

Yes, there's a lot of information. But, not one chapter c
one word is dull or difficult to follow or complicated. Prove i
yourself. Visit your computer store. Open the ELEMENTAR
APPLE. Read a page of the introduction, then flip it open
anywhere and read a paragraph or so. You'll find it's as
understandable, as helpful and as marvelous as we say.

If you, ora memberof yourfamily, is an Apple beginn
this is the book you need. It'll teach you everything you war
know, in the way you want to learn.

Only $14.95. At computer and book stores, or

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• OS-9 Assembler

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• 1 MB 5V4" Floppy Disk Drive

• DMA Double Density Floppy Disk Controller

• OS-9 Debugger

• OS-9 Assembler

GIMIX offers you a

38 MB WINCHESTER SYSTEM

HARDWARE FEATURES:

• 2MHz 6809 CPU

• 512KB Static RAM

• 8 RS232C Serial Ports

• 2 Parallel Ports
SOFTWARE FEATURES:

• OS-9 LEVEL TWO Multi-User
Operating System

• OS-9 Debugger

19 MB WINCHESTER SYSTEM

HARDWARE FEATURES:

• 128K Static Ram

• 2MHz 6809 CPU

• 19 MB 5V4" Winchester DMA Subsystem
SOFTWARE FEATURES:

• OS-9 LEVEL TWO Multi-User
Operating System

• OS-9 Text Editor

128KB MULTI-USER SYSTEM $6997.39

HARDWARE FEATURES:

• 2MHz 6809 CPU • 2 RS232C Serial Ports

• DMA Double Density Floppy Disk Controller • Dual 8" DSDD Floppy Disk System

• 128KB Static Ram

SOFTWARE FEATURES: Your choice of either UniFLEX or OS-9 LEVEL TWO. Both are Unix-like
Multi-User/Multi-Tasking Operating Systems.

56KB FLEX/OS-9 "SWITCHING" SYSTEM $4148.49

HARDWARE FEATURES:

• 2MHz 6809 CPU • DMA Double Density Floppy Disk Controller

• 56K Static Ram • 2 Built-in 5 V4" 40tr DSDD Disk Drives

• 2 RS232C Serial Ports (80 Track DSDD Drive Option . . add $400.00)
SOFTWARE FEATURES:

• GMXBUG monitor — FLEX Disk Operating System

• OS-9 LEVEL ONE Multi-tasking operating system for up to 56K of memory

WINCHESTER SUBSYSTEMS

Winchester packages are available for upgrading current GIMIX 6809 systems equipped with DMA controllers, at least one
floppy disk drive, and running FLEX, OS-9 LEVEL ONE or OS-9 LEVEL TWO. The packages include one or two 19MB (unformat-
ted) Winchester drives, DMA Hard Disk Interface, and the appropriate software drivers. The Interface can handle two SVi"
Winchester Drives, providing Automatic Data Error Detection and Correction: up to 22 bit burst error detection and 1 1 bit burst
error correction.

Dual drives can be used together to provide over 30 MBytes of on line storage -- or use one for back-up of the other. (More
convenient and reliable than tape backup systems.

#90 includes one 19MB Drive, Interface, and Software $4288.90

#91 includes two 19MB Drives, Interface, and Software $6688.91

Contact GIMIX for systems customized to your needs or for more information.
50 HZ Export Versions Available

GIMIX Inc. reserves the right to change pricing and product

specifications at any time without further notice. 1 337 WEST 37th PLACE

CHICAGO, ILLINOIS 60609

GIMIX® and GHOST® are registered trademarks of GIMIX Inc. ,o^ ov qo-? cc-in

FLEX and UniFLEX are trademarks of Technical Systems Consultants Inc.
OS-9 is a trademark of Microware Inc.

Eimix

inc.

TWX 910-221-4055

1982 GIMIX Inc.

Emulates these teminals

IBM 3101
DEC VT100, VT52
Oata General D200
ADDS Regent 20, 25, 40
HazeWne 1400, 1410, 1500
Lear Siegler ADM-3A, ADM
TeleVMeo 910
Teletype Model 33 KSR

Apple is a trademaiti of
Apple Computei; Inc.

New File Transfer Language

Your host compu

won't know the difference!

Softertn provides an exact teftninal emulation
for a wide range of CRT terminals which interface
to a variety of host computer systems. Special
function keys, sophisticated editing features,
even local printer capabilities of the terminals
emulated by Softerm are liilly supported. Softerm
operates with even the most discriminating host
computer applications including video editors.
And at speeds up to 9600 baud using either a
direct connection or any standard modem.

Unmatched file transfer capability

Softerm offers file transfer methods flexible
enough to match any host computer requirement.
These include character protocol with user-
definable terminator and acknowledge strings,
block size, and character echo wait, and the
intelligent Softrans^ protocol which provides
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data. The character protocol provides maximum
flexibility for text file transfers. Any type file
may be transfered using the Softrans protocol
which provides automatic binary encoding and
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A FORTRAN 77 source program is supplied with
Softerm which is easily adaptable to any host
computer to allow communications with Softerm

using the Softrans protocol.

Softerm file transfer utilizes an easy to use
command language which allows simple defini-
tion of even complex multiple-file transfers with
handshaking. Twenty-three high-level commands
include DMt CATALOG, SEND, RECEIVE,
ONERR, HANGUP, MONITOR and others which
may be executed in immediate command mode
interactively or from a file transfer macro com-
mand file which has been previously entered
and saved on disk.

Built-in utilities

Softerm disk utilities allow DOS commands such
as CATALOG, INIT RENAME, and DELETE to be
executed allowing convenient file maintenance.
Local file transfers allow files to be displayed,
printed, or even copied to another file without
exiting the Softerm program. Numerous editing
options such as tab expansion and space com-
pression are provided to allow easy reformatting
of data to accommodate the variations in data
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accessed by a user-assigned name and specify

BREAK

CATALOG

CHAIN

CONFIGURE

CONNECT

CONVERSE

DIAL

END

HANGUP

LOG

MONITOR

NOLOG

ONERR

PAUSE

PROMPT

RECEIVE

REMARK

RETRIES

SEND

SPECIAL

SPEED

TIMEOUT

XMIT:WAIT

Supports tliese
interface txiards

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Apple Parallel Printer

Apple Serial Interface

' Apple Super Serial Card

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Computer Stop Omniviston'"

M&R Sup'R7erminar

STB Systems STB-80"

Videx Videotemi"

Vista Computer Vision 80™

Wesper Micro Wizard 80™

the serial interface parameters to be used.

Online Update Service

The Softronics Online Update Service is pro-
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fixes for user-reported problems using the
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as well as a convenient distribution method for
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user-contritxjted keyboard macros, file transfer
macros, and host adaptations of the Softrans
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Most advanced communications
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Just check Softerm's 300 page user manual.
You simply can't buy a more sophisticated
package or one that's easier to use. Available
now for only $150 from your local dealer or
Softronics, Inc.

SOFTRONICS

6626 Prince Edward, iVIemphis.TN 38119.901-755-5006

MICRO

No. 57 - February 1983

iAIOK)

February HigKlights

Expanding your knowledge of computer languages — or
just increasing your familiarity with many of them — can
help improve your programming skills. This month's
issue covers FORTH, Pascal, APL, and LISP, and provides
you with a valuable information sheet of language
packages offered by seventy vendors.

"EDIT, An Atari FORTH Screen-Oriented Editor" by
Mike Dougherty (p. 47) uses the Atari 800 display as a text
window into a FORTH disk screen. You can use Atari's
special function keys to prepare FORTH applications. In
"Apple Pascal Hi-Res Screen Dump" |p. 54), Robert
Walker presents a high-resolution graphics screen dump
for Apple Turtle graphics to the Epson printer with
Graphtrax. Terry Peterson discusses the history and ad-
vantages of APL, a language known for its high execution
speed, powerful features, yet cryptic character set — read
"APL on the SuperPET" (p. 43). "The World According to
LISP" by Steve Cherry (p. 65] is a good introduction to
LISP, a language many computerists consider strange and
obscure. Cherry outlines the major strengths and features
of LISP, as well as its structure.

Commodoie

In addition to the SuperPET article in our feature sec-
tion, we have several PET articles and one on the VIC-20.
"Microcomputer- Aided Instrumentation" (p. 89) by
Deborah Graves, et. al., is a continuation of our series on
Microcomputers in a College Teaching Laboratory (Part
rv) . Learn how to interface a microcomputer to two types
of scientific instruments — a spectrophotometer and a
chromatograph. If you want to convert Tiny PILOT to
your 8K PET, read "More on Tiny PILOT" by Arthur
Kunkins (p. 78). The author solves a few tricky problems
and provides detailed explanations of some of the com-
mands. David W. Priddle provides a utility program in
"IEEE-488 Control of PET/CBM" (p. 11). You can add
four new commands to your PET/CBM to make it an ef-
fective, inexpensive controller for use with many scien-
tific instruments. The program requires 4.0 BASIC. And
this month we present the third installment of Jim
Strasma's "It's All Relative" (p. 33|. }im explains how to
use the key file as an index into a relative file. He uses, as
an example, a powerful mail-list package available to the
public. Our VIC-20 contribution describes the hardware
and software needed to interface RS-232 devices to Com-
modore's VIC computer. See Michael V. Tulloch's article,
"An RS-232 Printer for VIC" |p. 17). You will also learn
how to convert RS-232 voltages to TTL, convert hex code
data to POKES, and use a CTS line from the VIC.

Apple

Along with the Apple articles in our language feature,
we offer an "Applesoft BASIC Routine for CAI" by Robert
Phillips (p. 81). With this routine you can trap errors,
isolate mistakes, and overlook typographical errors. Mr.
Phillips also discusses some uses for a match routine, and
presents just such a routine in BASIC.

Columns

This month's column on the Color Computer shows
you how to interface your machine-language routines with
BASIC (p. 92). John Steiner discusses the use of a RAM
hook and presents a routine that interfaces with the LIST
and LLIST commands to page a list on the screen. Tim
Osbom presents BUILDIT (Apple Slices], a routine that
makes programs external to VisiCalc create and access
VisiCalc worksheet files (p. 95). Whether you are a begin-
ner or pro, you can learn something from this program.
Paul Swanson, in From Here to Atari (p. 31] discusses
languages available for the Atari and answers several
readers' questions on hardware. Commodore 64 fans will
want to read Loren Wright's comments on the system's
exciting sound capabilities [p. 71). He takes a look at
music software, including Synthy 64, a musical composi-
tion program from Abacus Software.

ilMCftO

NEW SECTION!

BEGINNING NEXT MONTH
Ttirn to page 112 for more information on
our new section for the SERIOUS NOVICE
appearing for the first time next month.

VIC BOOK!

Turn to PET Vet, page 73, for details on our
soon-to-be-published book for the VIC.

No. 57 - February 1983

MICRO

Announcing * ,

Th^ best 6502 Assembler in the World

Now. The kind of high-level
Aipport you'd only expect
tofind%n a malhlrame

ORCA/M {Hayden'i (^t'/ 't
Relocatable Code/ v he-

for Micros) lets you

sopljjsticated applh 'i'" -
with the speed and • ' *. f
high-level language . tift.ir
the control and effi KTL.thit
only assembly tang 1 1 . ir'
Q§/e. *

Here's what ORCA M gives
you:

The Assembler

Macro language features

o Conditional sssemT. t

source and macro ■ '••
o Separate soufte ar I '■ a ri ■

files
o Nestable macros
o Parameter mid-atn ■■. or il

string search f unct i <
o SymboWfc paramet* ■

assignment •

o Numeric, string, ar^i i-r ik ,i

type parameters
o Parameter subscn I'l ^
o Global ^mmunicci t

between macros
o Macro expansion I t* nt'ol
o Count, length and ,!:•

parameter-atf'hut' ' ■■'■.Pa

Extensive Macro Libraries

Memory Constant
Declarations:

Inti-'jer
' Cnatacli ■
- •-nar-bjteii'teg* r
' H'-'Xucfeciii .»
■ [ kiut'r q Pj rt

Relocatable obiect module
generation

Fast assembly directly to
disk

Program segmentation :
■ SflcctiveW absembtf individ-
ij ii sjhroiit'nes
Glooal and oi''d> scopt. ot
s.mbols

The Linker

Produce executable binary

files from relocatable object

modules

Link routines from library

files

Link subroutine
re-assemblies

Define a new origin for pre-
viously assembled code

Invoke at assembly time or
byCommand

Subroutine libraries.

FioritiPvj fftfnt anddoub'e
prprrsrop roufnes •
Tr in(^ondfc'RT?liLJiirt'Or»%
H and'uros'jijphcs
P/'jItipIp pr-^L-s.! in rntpgpr
mith •

Irriit and w.tpor

The Editor

Co-resident screen editor:

''< Gl utidt sparcn and replaco
'B'Of.krnovF •

. Entrv I'f t lon keyboatrf
cnur..''teri

Supports lower case
adapters and shift-kfy *
modification • *

80-cofumn: fiariz^i||fl * m *
scrolling with 4^9pkinA
displays •*

TheSysterr ,- _

Monitor: transparent con-
trol of systpm from one
command Eavef
Extended Disk Commands:

- Fi(«"'crpy
■ F'lc undetete
' Cdtalogsorl
'iVtidcard tilendnes

Disk ZAP: Built-in disk
sector editor

OptimFzed DOS 3.3 compat-
ible operating systent
Operating system interface.

" Suuports d variety >Ti
rur'.'igurattona
User-nodtdabte tQdllow link
aqr nf custon^ dnwrs for "
F»-rpner3ls

64fcEIAM supported, •
48k required'

• Tr £ jnique 4rrayot t&atjrus
^r 1 * ^nction*' sp(.dM for
tjt'lf*[re pcwec of ORCA j*
i[ ■• I'p-sseri

All fpatures tire doruniented
ctearlv jnl i-'^ten-iv'Bly Zotno-
I'StiogbTUi the s.ibioj'iino
'ind n*cro Irbr^nps a"! Wf II
dS tn^- opi-'.nng •^•■ter-i, I'.c
II ''lud«=d

ORCA. !t yL^ij'rt.' sc rioiis dbi'fit
d^t'opi!-igtj'j02*oftWfjr»» its

the fane tjhjv

•

A^laBi' 'r^rr \o*r 1'a: j|

de^ler^Ld^

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STAFF

President/Editor-in-Chief
ROBERT M. TRIPP

Publisher

MARY GRACE SMITH

Editorial Staff

PHIL DALEY — Technical editor
JOHN HEDDERMAN — Jr. programmer
MARJORIE MORSE — Editor
JOAN WITHAM — Editorial assistant
LOREN WRIGHT — Technical editor

Graphics Department

HELEN BETZ — Director

PAUU\ M, KRAMER — Production mgr.

EMMALYN H. BENTLEY — Typesetter

Sales and Marketing
CATHI BLAND — Advertising manager
CAROL A. STARK — Circulation mgr,
LINDA HENSDILL — Dealer sales
MAUREEN DUBE — Promotion

Accounting Department
DONNA M. TRIPP — Comptroller
KAY COLLINS — Bookkeeper
EILEEN ENOS — Bookkeeper

Contributing Editors
CORNELIS BONGERS
DAVE MALMBERG
JOHN STEINER
JIM STRASMA
PAUL SWANSON
RICHARD VILE

Subscription/Dealer inquiries
(617)256-5515

DEPARTMENTS

February Highlights

Editorial

Updates

From Here to ATARI

PET Vet

CoCo Bits

95 Apple Slices

Reviews in Brief

101

Software Catalog

103

Hardware Catalog

104

6809 Bibliography

105

Information Sheet

109

Data Sheet

111

Advertiser's Index

112

Next Month In MICRO

No. 57 • February 1983

NO. 57 FEBRUARY 1983

IMCftO

Advancing Computer Knowledge

LANGUAGE FEATURE

42 SuperPET APL Terry Petersen

^^ An unusual, but powerful, fast, and memory-efficient language

A J EDIT: An Atari FORTH Screen-Oriented Editor Mike Dougherty

^ ' A big improvement over the APX line editors

54 APPLE Pascal Hi-Res Screen Dump Robert d. waiker

^^ Dump the high-resolution graphics screen to your printer

CO An Introduction to FORTH Ronald W. Anderson

^^ All about Reverse Polish Notation, colon definitions, and other FORTH features

CO FORTH for the 6809 Ronald W. Anderson

^^ A lool< at CCFORTH, figFORTH, and several FLEX-based systems

gc The World According to LISP Steven cherry

^^ A powerful language suited to robotics and artificial intelligence

I/O ENHANCEMENTS

-i -i Improved IEEE-488 Control for PET/CBM David w. Priddie

' ' More precise control of the bus, without using logical files

H 7 VIC RS-232 Printer i^ichaei v. Tuiioch

' ' Interface the Radio Shack Quick Printer and other RS-232 devices

op PROM BASIC for the C1 P David a. Jones

^^ Increase the 01 P's performance without a disk drive

OQ Indirect Files Under OS-65D Richard L Tretheway

^^ Use the indirect file to merge programs, perform warm starts, transfer programs.

BASIC AIDS

oo It's All Relative, Part 3

Using Commodore's Relative Records Jim strasma

Use a key file as an index into a relative file

oy A Binary Search Routine Alfred j. Bruey

^ ' Two demonstration programs illustrate this technique

Af) BASIC Renumber for OSI Paul Krieger

^^ Renumber programs in memory and save to tape

EDUCATIONAL UPDATES

JA 68000 Program Control: Branch and Jump

Instructions JoeHootman

78 More on Tiny PILOT for the PET Arthur Hunkins

81 A BASIC Match Routine for CAI Robert Phuiips

86 An Overviev\/ of Educational Softv\/are George Gerhoid

QQ Microcomputers in a College Teaching Laboratory,

^^ Part 4 Deborah Graves, Richard H. Heist, Thor Olsen, Howard Saltsburg

MICRO 5

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About the Cover

Aquarium personnel now use micro-
computers extensively for research,
education, and cataloging data. The bar
graph on this month's cover is a sample
output from a computer used to moni-
tor levels of toxic substances in ocean
water. Other ways that microcomputers
are being employed to improve the
marine environment are as diverse as
tracking whale migration patterns and
feeding sites to regulating tank
feedings with tidal rhythms.

Special thanks to the research
department at Boston's New England
Aquariaum for the time they spent
with us discussing their work.

Cover photo: Phil Daley
Cover Graphic: Generated by program
written by Art Arizpe

JMCftO is published monthly by:
MICRO INK, Chelmsford, MA 01824
Second Class postage paid at:
Chelmsford, MA 01824 and additional

mailing offices
USPS Publication Number: 483470
ISSN: 0271-9002

Send subscriptions, change of address, USPS
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MICRO INK
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/MCftO

Editorial

Oiir language f eaUire this month provides
an appropriate forum for our Editor-in-
Chief Bob Tripp, and Technical Editor
Phil Daley, to express their opposing
views on BASIC. It won't take long to
figure out who is pro and who is con.
What are your thoughts on BASIC?

Too Basic or Not Too Basic

According to John Kemeny, one of
the originators of BASIC, the main in-
tent was to provide the user with
friendly access to the computer. This
emphasis on user friendliness is the key
to BASIC'S popularity. The key word in
Beginner's All-purpose Symbolic In-
struction Code is the first one; more
microcomputer programmers start
with BASIC than any other language.

Without BASIC the microcomputer
world would never have gotten off the
ground. Its simplicity, forthright clarity,
memorable mnemonics, and inter-
active friendliness combine to make it
the best all-round microcomputer pro-
gramming language. When the micro
had only 4K of ROM and 2K of RAM,
BASIC was a necessity; even now with
64K- and 128K-RAM machines, loading
a monolith language returns you to
limited memory constraints.

Other languages, such as FORTRAN
and COBOL, make it easy to do pro-
gramming and to understand the pro-
gram. Unfortunately, microcomputers
don't do them justice, and all imple-
mentations become subsets of the
mother tongue.

FORTH and assembly language
overcome many of the limitations of
BASIC — especially its slowness — but
they are incomprehensible jibberish to
most folks, sometimes including the
person who wrote the program.

I must also mention Pascal, a fine
structured language, but the most ex-
asperating language in which to write a
program. The disk accesses, even with
three drives, are incredible. The
routine — load the editor, load the file,
change the file, save the file, load the
compiler, compile the program, run the
program, note the mistakes, load the
editor — is enough to addle your
brains. Any program that knows
enough to tell you that you forgot a
semicolon on the previous line, should
be smart enough to insert one for you!

Give me BASIC any day: load the
program, run, and make changes with
no delays. It is the only user-friendly
language amongst the lot!

Phil Daley

Much Too Basic and
Too Much BASIC!

BASIC was designed to allow a stu-
dent with a TTY terminal to write simple
programs on a time-shared mainframe,
and thousands of people received their
initial introduction to the computer via
BASIC. It served these purposes well.
However, it is not a good language for
the microcomputer. The use and abuse
of BASIC has caused software develop-
ment to lag behind hardware develop-
ment. The fundamental problems are:

1. BASIC does not make effective
use of screen capabilities. Positioning
the cursor is awkward, reading the cur-
sor position is difficult, and material
appearing on the display is virtually
impossible to access from a program.

2. Input routines do not permit er-
ror checking of input, do not support
interaction with the operator, do not
provide support for other input devices,
and are generally limited in capability.

3. BASIC does not make effective
use of disk capacities. Only the most
basic disk file structures are supported,
and these often have restrictions.

4. BASIC does not support large
programs well. The use of line numbers
as labels makes it difficult to maintain
and modify large programs. As programs
grow, they become increasingly hard to
modify, document, and imderstand.

5. BASIC does not have simple
techniques for manipulating string-
oriented material. It 'thinks' only in
decimal, which may be appropriate for
some calculations, but is awkward for
many requirements of hexadecimal-
oriented computers.

6. BASIC is slow. The overhead in-
volved with interpreting and re-
interpreting every line during program
execution can make even the most effi-
cient microcomputers appear sluggish.
There is also a high overhead in its
memory requirements.

BASIC is simply too basic for many
situations. Some programs would be
more beneficial written in an alter-
native language. BASIC should be used
for introductory programming, short
programs, numerical calculation pro-
grams, and limited input requirements.
It should not be used for long programs,
disk and video-oriented applications,
non-numerical programs, and special
devices; in these cases, alternative ap-
proaches should be considered.

Bob Tripp

No. 57 - February 1983

MICRO

BUSICALC

BGSICALC A Honey of an Electronic Spreadsheet

Why electronic spreadsheet programs?

Electronic spreadsheet programs allow the user to create a gridsheet,
spreadsheet, worl<sheet, or any other table of information, using the
memory of the computer as pencil and paper The computer display or
terminal acts as a window through which the user views the information
as it is entered. Textual information (such as headings), numerical values,
and formulas can easily be entered into the spreadsheet.

o-M-a-o H a n H H n H H o B pg E5

Efaa a a b a a a la a ora tai&i^

For Commodore 64

For Commodore VIC 20

For Commodore PET/CBM 40 columns

For Commodore CBM 80 column/SuperPet

BGSICALC Your Computer Drone for Repetitive Calculations

The outstanding advantage of using a computer is that it acts not only
as a pencil and paper but as a perfect eraser and an automatic calculator
The user can quickly and easily make any number of alterations to the
data within the table. The BUSICALC will evaluate any formula using the
data that has been entered. Further, it retains the formulas and displays
the resulting value. With BUSICALC controlling the entry of data, provid-
ing a comprehensive memory, and performing arithmetic, the preparation
of a spreadsheet is faster and more accurate than If it were prepared
by hand.

BGSICALC With the Sting Removed from the Prices

BUSICALC 20 only $49.00 for the VIC 20

BUSICALC 64 only $69.00 for the CBM 64

BUSICALC 40 only $79.00 for the original 40 column PET/CBM

BUSICALC 80 only $89.00 for the original 80 column CBMs and SuperPets

BUSICALC AVAILABLE NOW FROM YOUR LOCAL DEALER

(800) 227-9998
FOR THE NAME OF YOUR NEAREST DEALER

California, Canada, Alaska and Hawaii please call (415) 965-1735

Skyles Electric Works

231G South Whisman Road
Mountain View, CA 94041

Europe please contact Supersoft, Winchester House, Canning Road, Harrow Wealdstone, Middlesex, England HA3 7SJ, Tel. 01 861 1166

/MCftO

Updates
and Microbes

In MICRO'S Commodore 64 Data Sheet [MICRO
55:109) most of the SID's registers were inadvertently
omitted. Here is a complete SID register list.

Voice 1

Voice 2

Voice 3

$D400

$D407

$D40E

Frequency, low* byte

(54272)

(54279)

(54286)

$D401

$D408

$D40F

Frequency, high byte

(54273)

(54280)

(54287)

$D402

$D409

$D410

Pulse w(idth, \o\N byte

(54274)

(54281)

(54288)

$D403

$D40A

$D411

Pulse w(idth, high nibble

(54275)

(54282)

(54289)

(bits 4-7 = 0)

$D404

$D40B

$D412

Voice Type: (bits 4-7)

(54276)

(54283)

(54290)

7 Noise

6 Pulse

5 Sawdooth

4 Triangle

3 Test

2 Ring modulate
(1 = on, = off)

1 Synchronize

Gate bit
(1 = start attack,
= start release)

$D405

$D40C

$D413

Attack/Decay

(54277)

(54284)

(54291)

Attack time (bits 4-7)

2 ms - 8 ms
Decay time (bits 0-3)

6 ms - 24 sec

Voice 1

Voice 2

Voice 3 Register Function

$D406

$D40D

$D414 Sustain/Release

(54278)

(54285)

(54292) Sustain level (bits 4-7)

x/15 proportion of peak
Release time
6 ms - 24 sec

Address

$D415

54293

Filter frequency
Bits 7-3 =
Bits 2-0 \o\N bits

$D416

54294

Filter frequency, high byte

$D417

54295

Resonance/Filter Voices
7-4 Resonance
3-0 Filter voices
3 external
2 voice 3
1 voice 2
voice 1

$D418

54296

Filter select/Master volume
7 voice 3 off
6 high-pass on
5 band-pass on
4 low(-pass on
3-0 master volume

$D419

54297

Paddle X {AID #1)~read only

$D41A

54298

Paddle Y (A/D #2)~read only

$D41B

54299

Digitized voice 3 w(aveform-read only

$D41C

54300

Digitized voice 3 envelope-read only

Let us know if you 've updated an atricle oi discovered a
bug. Send a note to: Updates /Microbes, MICRO, P. O. Box
6502, Chelmsfoid, MA 01824. iMCftO

VIC-20

SOFTWARE
SPECIALS

NEW

A 100% machine code game with colorfui
graphics, music, sound and a funny looking
turtle to entertain your entire family!
By Thomas Kim and Jimmy Huey ONLV $15.95

II I iiiiiiiii II ii f II iiiiiiiii I ill nil liiiii III wiiiim

'"I V'^j;;j''^K*
FftOM iNrcMsnNG sonumnc

A. If

VIC-20

FROM TRONIX

SWARM!

Another fast action game written
entirely in machine language from
Tronix, Insects Invade your Vic!

Cassette $29.95

DUST COVERS - $7.95

For Vic-20 or Vic-64

* Waterproof

* Brown Color

' Commodore Logo
Protect your investment!

^^°^ MARTIAN
JV SOFTWARE

STAR COMMAND

' Intergalactic Combat! * Space Conflict

* All Macfiine Language
Cassette $16-95

_^-* INTERESTING SOFTWARE

' P 21101 S. Harvard Blvd., Torrance, CA 90501
(213) 328-9422
Visa/MC/Check/Money Order Add $2.00 Postage & Handling

CA residents add appropriate sales tax Dealer Inquirers Invited

Write tor free Catalog

No. 57 - February 1983

MICRO

FOR COMPLETE GRAPHICS:

UersakUn'ter

EDUCATION

Whether you are a
teacher, an artist, an
engineer, a

programmer, or a ]

hobbiest with iittle or no
programming experience,
the VersaWriter is the
answer to your graphics
need. With the VersaWriter
expioring the worid of micro
computer graphics is as easy
as tracing. The VersaWriter

ARTIST

GAME PROGRAMMER

doesn't just trace
a picture though. With
simpie one i<ey com-
mands you can add
coior and text to your pic-
tures, move objects across
the screen, mai<e scale
drawings and even draw
with different size brushes.
The VersaWriter is as iimitiess
as your Imagination.

For complete graphics on your Apple II/II+, or IBM PC, the Versa Writer from Versa Computing, Inc. is your answer.
Complete hardware/software system ready for use - $299.

Send for information
on the complete line
of VE^^iAVik^i & Grophlcs
Products

compuanc, inc.

Dealer
Inquiries
Welcome

3541 Old Conelo Road, Suite 104 • Newbury Parl<, CA 91320 • (805) 498-1956

MICRO

No. 57 - February 1£

Improved IEEE-488 Control

for PET/CBM

by David W. Priddle

This utility program for PET/CBIVI
with 4.0 BASiC adds four new
commands that improve the I/O
control of the IEEE-488 bus.
With more complete control of
the bus, the PET/CBIVI becomes
an effective, inexpensive
controller for a wide variety of
scientific instruments.

I/O Control

requires:

4.0 PET/CBM or SuperPET

The IEEE-488 bus is available on a wide
variety of measurement and signal-
generating equipment from a number
of large manufacturers including
Hewlett-Packard, Tektronix, and
Fluke. Some of these companies also
supply sophisticated and expensive
microcomputers and "programmable
calculators" that can act as instrument
controllers using the 488 bus. The
PET/CBM micros cost considerably
less and are, therefore, an attractive
alternative for use with scientific
instruments. The disadvantages of the
PET/CBMs are twofold: the graphics
resolution is poor when compared to a
Tektronix 4051, which has a 1024 x
780 point addressable display; and
second, the I/O techniques using
"logical files" have limitations when
used with equipment other than disk
drives and printers.

The resolution problem has been
tackled in a variety of ways, from sim-
ple plotting programs that offer a small
improvement, to the addition of expan-
sion graphics memory. The problem of
improving the I/O control is the object
of this current utility program.

The Tektronix 4051/4052 systems
offer two levels of control. High-level
control of the bus uses the commands:

PRINT@X,Y:a,b,c,etc,
INPUT@X,Y;a,b,c,etc,

Listing 1: Assembly Listing

0001

0000

; 'printP27

0002

0000

;aug 26,1982

0003

0000

*=$O030

0004

0030

;start

o£

strings

000S

0030

*=$0034

0006

0034

; top

£ basic

0007

0034

*=$007B

0008

0070

chrget

;jump to start

0009

0070

*=$0O76

0010

0076

chrgot

0011

0075

*=S027a

0012

027a

tenip3

* = * + !

;y store

0013

027b

temp4

♦ = ♦ + 1

;i/o f lag ,0=output , $22=inpu

0014

027c

temps

♦ = * + l

; rby buE£er

0015

027d

temp6

* = * + l

.-quote delimiter

0016

027e

temp7

* = * + l

;colon delimiter

0017

027f

*=$7e47

0018

7e47

setup

Ida

»$7e

;sys 32327 to setup

0019

7e49

sta

$31

;change top of strings

0020

7e4b

sta

$35

;and top o£ memory

0021

7e4d

Ida

»$46

0022

7e4f

sta

$30

0023

7e51

sta

$34

0024

7e53

Ida

»$4c

;put jmp (S4c) in chrget

002S

7e55

sta

SI?.

0026

7e57

Ida

»$e5

.-adjust to point at start

0027

7e59

sta

$71

0028

7e5b

Ida

f$7e

0029

7e5d

sta

$72

0030

7e5f

rts

0031

7e60

input4

jsr

chrget

.-go past delimiter

0032

7e63

input

Idx

ll$00

0033

7e65

£1

input2

jsr

$£lc0

.-get byte £rom ieee

0034

7e68

sta

$027c,x

.-store byte in buffer

0035

7e6b

inx

0036

7e6c

bit

$10

.-check, was '\' used ?

0037

7e6e

bmi

inputs

;'\' so don't check for cr

0038

7e70

cmp

}$0d

.•check for cr

0039

7e72

beq

inputs

,-cr, so end input

0040

7e74

£a

inputs

cpx

»250

.-check iE full

0041

7e76

beq

inputs

,-buffer full so quit

0042

7e78

Ida

$96

.-status word

0043

7e7a

and

t%01000O00

.-check eoi

0044

7e7c

beq

input2

.-no eoi so continue

0045

7e7e

inputs

Ida

#$22

;quote

0046

7e80

sta

$027c,x

0047

7e83

inx

0048

7e84

Ida

»$3a

.-colon

0049

7e86

sta

$027c,x

0051

7e89

7£

jsr

varval

.-assign value

0052

7e3c

jsr

chrgot

.-check Eor

0053

7e8f

bne

input4

0054

7e91

jmp

prints

;input finished

0056

7e94

inout

Ida

l$O0

.-set status word =

0057

7e96

sta

$0096

0058

7e98

jsr

ScSdl

;get byte to .xr

0059

7e9b

stx

$d4

.-pa

0060

7e9d

stx

$b0

;output device number

0061

7e9f

stx

$af

.-input device number

0062

7eal

Ida

temp4

.-check i/o flag

0063

7ea4

£0

beq

inout2

.-output, send listen

0064

7ea6

txa

.-put pa into .a

0065

leal

£0

jsr

$f0d2

;talk addr routine

0066

leaa

clc

0067

7eab

bcc

print2

;branch always

0068

7ead

inout2

txa

.-put pa into .a

0069

7eae

£0

jsr

$£0dS

.-listen addr routine

007B

7ebl

print2

jsr

chrgot

.-check for semicolon

0071

7eb4

cmp

#$3b

No. 57 - February 1983

MICRO

where X is the IEEE-488 device primary
address (PA], Y is the secondary address
(SA), and a, b, and c are the variables to
be output or input. The utility program
presented here follows this syntax with
the single change of using a semicolon
or a backslash in place of the colon.
(The PET/CBM recognizes the colon as
a statement separator. ) This syntax has
the obvious advantage that "logical
files" are not used: there is no need to
"OPEN" or "CLOSE" files. The out-
put has the following syntax:

PRINT@4,0;"hello there",a,b%,c$

This command string sends to the 488
bus the primary listen address 4 and the
secondary address (with the 488 ATN
line set low — true), followed by the
ASCn string "hello there", the current
values of the variable a, integer variable
b%, and string variable c$. A carriage
return is sent and the 488 bus is cleared
by an UNLISTEN/UNTALK command.

If a backslash is used in place of the
semicolon, a line feed is also sent with
the carriage return. If a printer with
device number 4 is coimected, the string
and variables will be printed.

The input command has the syntax:

INPUT@29,24;a$

This command string sends the pri-
mary talk address 29 and the secondary
address 24. Data is then input to the
PET/CBM until a carriage return is
received, the 488 EOI (end or identify)
line is set low ( = true), or the input
buffer is full. The data is then assigned
to the variable a$. There are three fea-
tures of this syntax that differ from the
standard PET/CBM INPUT#: no logi-
cal files are used; the input buffer used
is located in the tape buffers and is set
to allow an input of 250 characters in-
stead of the usual limit of 80 charac-
ters; and the command can be executed
not only in a program, but in immedi-
ate mode. This feature is useful when
controlling instruments. In addition, if
a backslash is used in place of the semi-
colon, the input will not terminate
when a carriage return is received. Any
carriage returns will simply be imbed-
ded in the string variable (in the above
case, a$]. Of course, numeric variables
can also be input with INPUT®. In
these cases the backslash should not be
used since the carriage return is an il-
legal character here.

The Tektronix systems also allow

Listing 1 (continued)

0072
0073
0074
0075
0076
0077
0078
0079
0080
0081
0082
0083
0084
0085
0086
0087

0089
0090
0091

0093
0094
0095
0096
0097
0098
0099
0100
0101
0102
0103
0104

0106
0107
0108
9109
0110

0111
0112
B113
0114
0115
0116
B117
0118

0120
0121
0122
0123
0124
0125
0126
0127

0129
0130
0131
0132
0133
0134
0135
0136
0137
0130
0139
0140
0141
0142
0143
0144
0145
0146

0148
0149
0150
0151
0152
0153
0154
0155
0156
0157

0159
0160
0161
0162
0163
0164
0165

7eb6
7eb8
7eba
7ebc
7ebf
7ecl
7ec3
7ec6
7ec9
7ecc
7ece
7ed0
7ed2
7ed4
7ed7
7ed9

7ee5
7ee8
7eea
7eec
7eee
7ef0
7ef2
7ef 4
7ef6
7ef8
7efa
7efd

7f0b
7f0d
7f0f
7fll
7fl3
7fl6
7fl9

7fle
7£21
7f23
7f 25
7f28
7f2b
7f2d
7f2£

7f32
7f35
7f37
7f39
7f 3c
7£3e
7£4P
7£43
7£45
7£48
7£4b
7£4e
7£51
7£51
7f53
7£56
7£58
7£5b

7£5e
7£61
7£63
7£66
7£68
7£6a
7£6d
7£70
7£72
7£75

7£78
7£7a
7£7d
7£80
7£82
7£85
7£87

£0 0e
c9 5c
£0 0a
20 dl c8
86 d3
86 a5
20 09 £1
20 48 £1
20 76 00
c9 5c
d0 04

££

ad 7b 02
d0 87
20 70 00

7edc 20 aa ba
7ed£ 20 b4 bb
7ee2 4c fa 7e

8c 7a
e6 77
d0 02
e6 78
a0 00
bl 77
c9 99
£0 0a
c9 85
£0 09
ac la
4c 76

02
00

7£00 a9 00

7£02 2c

7£03 a9 22

7£05 8d 7b 02

7£08 20 70 00

c9 40
£0 85
c9 21
£0 06
20 £7 7£
4c £a 7e
ad 7b 02

7£lc d0 6e

20 70

c9 3b

£0 31

20 £7 7£

20 dl c8

86 d4

a9 00

20 d7 £0

20 76 00
c9 3b
£0 0a
20 dl c8
86 d3
86 a5
20 09 £1
a9 £d
2d 40 e8
8d 40 e8
20 48 £1
20 70 00

£B a7

20 £7 7£

a9 02

0d 40 e8

Od 40 e8

20 76 00
£0 97
20 70 00
c9 ab
£0 0e
20 £7 7£
20 dl c8
86 a5
20 09 £1
4c 5e 7£

a9 34

11 e8
c8

beq atnhi2
cmp SS5c
beq atnhi2
jsr $c8dl
stx $d3
stx $a5
jsr $£109

atnhi2 jsr $£148
jsr chrgot
cmp #$5c
bne print4
Ida #$££
sta $10

print4 Ida temp4
bne lnput4
jsr chrget

jsr $baaa
print3 jsr Sbbb4
jmp bacbas

start sty temp3
inc $77

bl bne b2
inc $78

b2 Idy #$00

Ida ($77), y
cmp S$99
beq b5
cmp l($85
beq al

bacbas Idy temp3
jmp chrgot

b5 Ida #$00
.byte $2c

al Ida JS22
sta te(np4
jsr chrget

cmp JS40

beq inout

cmp 3$21

beq rbywby

jsr chrdec

jmp bacbas

rbyv;by Ida temp4

bne rby

;check £or \

;get byte (sa) to .xr

;sa

; sa into leee buffer

;send sa

;clear atn (high)

;check £or \

;send cr,end input on cr

;send cr/lf, ignore cr on inp

;check if input
; input data

;send data

;unl buss, reset i/o

freturn to basic

;save y

;check for print

; check for input

/restore y
;back to basic

;set output flag
; dummy op (bit = S2c)
;set input flag (")
/store flag

/check for 9

/check for 1

/reset chrget pointer

/check i/o flag

wby jsr chrget

cmp ll$3b

beq out2

jsr chrdec

jsr ScSdl

stx $d4

Ida J$0(1

jsr S£0d7

jsr chrgot

cmp }$3b

beq atnhi

jsr Sc8dl

stx $d3

stx Sa5

jsr $fl09

atnhi Ida #$£d

and $e840

sta $e840

jsr $fl48 /atn o£f (high)

jsr chrget /look past semicolon
;z flag set if binary zero or colon

beq bacbas /no bytes to send, bacbas

jsr chrdec

out2 Ida 5S02 /set nrfd high again

ora $ea40

sta Se042

/check for semicolon
/no addr sequence

get byte to .xr
prim addr save
send pa "as is"
set atn, send pa

/check for semicolon

/no s.a. so clear atn
/get byte ( sa ) to .xr
/sa store

/ieee output buffer
/send byte to ieee
/set nrfd low

outbyt jsr chr-jot
beq bac^'ios
jsr chr.^et
cmp JSab
beq out3
jsr chrdec
jsr Sc8dl
stx Sa5
jsr Sfl09
jmp outbyt

out3

20 dl
86 a5
20 09 fl
a9 3c
11 e8

Ida t%0011fll0B

sta $e811

jsr $c8dl

stx $a5

jsr Sfl09

Ida t%00111100

sta $e811

/check for en.i o£ statement
/ look at next chr
/check for minus sign

/reset chrget
/get byte to .xr
;to ieee buffer
/send to ieee

/bit 3

/set eoi true

/get byte

/send it
/bit 3
/reset eoi

MICRO

No. 57 - February 1983

Listing 1 (continued)

0166

7f8a

b[)l

outbyt

/branch always

0168

7f8c

rby

Ida

»S22

;set up bu££er

0169

7f8e

sta

teinp6

0170

7f91

Ida

J$3a

0171

7f93

sta

temp7

0172

7f96

jsr

SO070

;go past (!)

0173

7f99

£1

jsr

Sflc?

;get byte from leee

0174

7f9c

sta

temp5

;get unasslgned byte

0175

7f9f

sta

$a5

;copy also to leee buffer

0176

7fal

jsr

chrgot

;check chrgot

0177

7fa4

bne

rby4

;no target variable

0178

7£a6

rby5

Ida

J$22

.-defeat housekeeping

0179

7fa8

sta

tempG

0180

7£ab

Ida

tS3a

0181

7fad

sta

temp7

0182

7fb0

rby3

Ida

»$fl8

;set ndac high

0183

7fb2

ora

$e321

al84

7£b5

sta

Se821

0185

7fb8

jmp

bacbas

0187

7fbb

7£

rby<t

jsr

varval

0188

7£be

0tl

jsr

chrgot

;check for

0189

7fcl

£0

beq

rbyS

0190

7fc3

jsr

cfirget

;go past delimiter

0191

7fc6

£1

jsr

S£lc(i

;get next byte

0192

7£c9

sta

temps

;store

0193

7£cc

sta

Sa5

0194

7£ce

7£

jmp

rby4

;assign value

0196

7£dl

varval

jsr

$cl2b

.-search for variable

0197

7fd4

sta

$46

.-returns in .a and .yr

0198

7fd6

sty

$47

.-variable pointers

0199

7fd8

Ida

$77

0200

7£da

pha

0201

7£db

Ida

$78

0202

7£dd

pha

.-save chrget pointers

0204

7£de

bit

$07

;var type, ££=str aa=numeric |

0205

7£e0

bmi

rby2

.-str if true.n flag set by

bit

0206

7fe2

Ida

»$7c

0207

7fe4

.by

te $2c

/dummy op code

0208

7£e5

rby2

Ida

tS7b

(Start buffer at quote

0209

7£e7

sta

$77

0210

7£e9

Ida

t$02

.-change chrget pointers

0211

7£eb

sta

$78

0212

7£ed

jabove

val

jes must

change if buffer moved

0214

7£ed

jsr

$b93c

.-assign var value

0215

7ff0

pla

.-reset chrget

0216

7ffl

sta

$78

0217

7££3

pla

0218

7££4

sta

$77

0219

7££6

rts

0218

7f£4

sta

$77

0219

7££5

rts

11222

7f£7

chcdec

Ida

$77

;ceset chrget pointer

[■223

7££9

dfi

bne

chrdl

0224

7££b

dec

$78

0225

7££d

chrdl

dec

$77

022(;

7£££

cts

488 bus control on a more primitive
level using the syntax:

WBYTE@X,Y:a,b,-c
RBYTEa.b

The WBYTE command means " write-
by te" and is implemented in this pro-
gram with the syntax:

PRINT!X,Y;a,b,-c

For those familiar with Tektronix, this
command behaves exactly as WBYTE.
The command sends (with ATN set]
the absolute primary address of the
value of X, and the absolute secondary
address of the value of Y. By

"absolute," I mean that the address is
sent as is and is not first converted to a
talk address (by setting bit 7), or a
listen address (by setting bit 6). The
byte variables a, b, and c are then sent
(without ATN). These one-byte vari-
ables (or expressions) must have values
between and 255 to be valid. The
minus sign before the variable c causes
the EOI line to be set as this byte is
sent. Depending on the particular
device, this may be necessary to signal
the end of transmission to the ad-
dressed device.

Note that the command does not
send UNLISTEN or UNTALK and the
addressed device(s) continues to take
part in transactions on the 488 bus.

This means that one talker and one or
more listeners can be set actively on
the bus with or without the controller
(the PET/CBM) taking part in the sub-
sequent data transactions. When the
process is finished, it may be necessary
to send UNL/UNT using the command:

PRINT!63,95;

This will force all previously addressed
talkers and listeners off the 488 bus.

The Tektronix RBYTE command
means "readbyte" and is exactly im-
plemented here using the syntax:

INPUTIa.b

The use of this command requires that
a 488 bus device must have been
previously addressed as a talker (using
PRINT! (PA), (SA);). Execution of the
command causes the talker to send a
single byte whose ASCII value is then
assigned by the PET/CBM to the
variable a, and then to send another
single byte, which will be assigned to
b. Any number or types of variables
may be specified and a single byte will
be input for each. If no variable is
specified, an unassigned byte will be
input and placed in location ($00A5]
where it may be PEEKed if desired.
Again, the device must be sent UN-
TALK (PRINT!95;) in order to remove
it from the bus.

This command is unlike GET# in
two important respects: again, no
logical files are used and INPUT! does
not send either an address sequence or
an UNTALK command. The GET#
command does not allow a talker to
stay actively on the bus because UN-
TALK is sent during each execution.
GET# goes through the addressing
routine each time before it gets a byte
from the 488 bus. These two aspects of
GET# can be merely an inconvenience,
or an absolute disaster, when attemp-
ting to use the PET/CBM to control ad-
vanced instrumentation. With one in-
strument we have used, GET# caused
the PET/CBM to receive only every
third byte sent because of the confusion
caused by the repeated addressing se-
quences. INPUT# could not be used
since more than 80 characters are sent
without either EOI or a carriage return.

This utility program mimics the
I/O procedures used by Tektronix and
thus allows the PET/CBM to send or
receive data using the simpler syntax of
PRINT®; and INPUT®; without

No. 57 ■ February 1983

MICRO

needing "logical files." It also permits
any single byte to be sent or received
(with or without ATN) on the 488 bus
using the syntax of PRINT!; and IN-
PUT! . More complete control of I/O
on the IEEE-488 bus allows the
PET/CBM to be used as a scientific in-
strument controller in applications
that are more difficult or impossible
without this program.

How to Use the PRINT®
Utility Piogiam

An assembler listing [listing 1) and
BASIC loader program (listing 2) are
provided for any PET/CBM with
BASIC 4.0 and 32K. The BASIC pro-
gram should be entered and run. This
will load the machine code into top of
memory, adjust the BASIC pointers to
protect the code, and attach itself to the
CHRGET routine. The utility program
may then be NEWed. Since the
machine code in this form is not
relocatable, it should be loaded before
any other BASIC program. There are
12 absolute addresses used that must
be changed if the program is re-

"■"'CQiUPU $EI\J$Ei:.

CARDBOARD 6
$87.95

An expansion interface tor ttie VIC-20.
Allows expansion to 40 K or accepts up
to six games. May be daisy ctiained for
more versatility.

CARDBOARD 3
$39.95

Economy expansion interface for
the VIC-20

CARD "?" CARD/PRINT
$79.95

Universal Centronics Parallel Printer
Interface for the VIC-20 or CBM-64.
Use an Epson MX-80 or OKI DATA or
TANDY or just about any other.

CARDETTE
$39.95

Use any standard cassette player/re-
corder Vifith your VIC-20 or CBM-64

CARDRITER
$39.95

A light pen with six good programs to
use Vifith your VIC-20 or CBM-64

Prices subject to change.
TO ORDER: P.O. BOX 18765

WICHITA. KS 67218
(316) 684-4660
Personal Checks Accepted (Allow 3 Weeks)
or C.O.D. (Add $2) Handling Charges $2.00

assembled for some other location such
as in an EPROM.

The four new commands are im-
plemented using some of the
PET/CBM ROM routines, but it was
not possible to use the jump address
table in ROM since only parts of the
I/O routines are used. The commands
support the full syntax error checking
for variable type and legal values, as
well as for punctuation.

When the commands are entered,
BASIC crunches the PRINT or INPUT
to the usual tokens ($99 or$85). When
BASIC executes the commands, the

utility program tests to see if a PRINT
or INPUT has been found. If either is
found then a further test is made to see
if they are followed by @ or ! and the
correct routine is then started. If
neither test succeeds, then control is
sent back to BASIC.

(EditoT's note: this approach slows
down the execution of BASIC programs
to varying degrees, depending on the
particular instructions involved. If you
don't need to use the commands for a
particular program, it is probably best
to turn the machine off before loading a
new BASIC program.

900

902

904

906

908

910

911

912

914

916

918

919

920

921

922

924

925

926

927

928

930

932

933

934

941

942

944

1000

1010

1020

1030

1040

1050

1060

1070

1080

1090

1100

1110

1120

1130

1140

1150

1160

1170

1180

1190

1200

1210

1220

1230

1240

1250

1260

1270

1400

1410

1420

1430

P
david

rem

rem '@' pu

rem addres

rem print?

rem inputs

rem input?

rem

rem ******

rem

rem print!

rem

rem print!

rem addres

rem don ' t

rem

rem input!

rem device

rem

rem (sa)

rem
datal69,l
datal69,2
data241,l
data6,165
datal24,2
datal50,3
data32,21
datal4,20
data72,24
data208,l
data2,230
datal33,2
data2,32,
data250,l
datal27,3
data240,l
datall2,0
datal71,2
datal27,l
datal41,l
data64,23
datal33,l
data2,169
data232,7
datal92,2
data71,16
datal33,l
datal65,l
restore
fori=3232
sys32327
end

Listing 2: BASIC Loader

rintg 4.2
priddle august 27,1982

ts atn low, ' ; ' or '\' puts atn high

ses converted to talk or listen as appropriate

(pa) , (sa) ;a ,b,c$, . . sends data and cr only

(pa) , (sa)\a$,b%,c. . sends data and cr/lf

(pa) , (sa) ;a$ ,b. . . input ends on eoi, buffer full or cr

(pa) , (sa)\a,b. . . input ignores cr

(pa) , (sa) ; (bytel) , (byte2) ,-(byte3) .. . minus sets eoi

(byte-) =expression with value 0-255
; (bytel).,. allowed if device has been addressed
; not allowed without either address or datum
ses sent 'as is' - not converted to talk or listen
forget to unt/unl the buss

a input single byte and assign to variable
a$,b... input single bytes and assign to variables
must be addressed with ' print ! (pa) , (sa) ; ' first

is optional in all cases if allowed by device

26,133,49
29,133,11
57,124,2,
,150,41,6
,32,209,1
2,209,200
0,240,24,
1,92,240,
1,32,118,
35,32,112
,119,208,
40,9,172,
112,0,201
26,173,12
2,209,200
0,32,209,
,240,175,
40,14,32,
69,52,141
7,232,16,
2,41,253,
65,32,118
,8,13,33,
6,250,126
41,141,12
5,119,72,
19,169,2,
19,208,2,

,133,53
3,169,1
232,36,
4,240,2
27,32,1
,134,21
144,4,1
10,32,2
0,201,9
,0,32,1
2,230,1
122,2,7
,64,240
3,2,208
,134,21
200,134
32,247,
247,127
,17,232
210,169
141,64,
,0,208,
232,141
,32,209
4,2,133
165,120
133,120
198,120

,169,70
26,133,
16,48,4
31,169,
18,0,20
2,134,1
38,32,2
09,200,
2,208,4
70,186,
20,160,
6,118,0
,133,20
,94,32,
2,134,1
,211,13
127,32,
,32,209
,32,209
,34,141
232,32,
29,169,
,33,232
,127,32
,165,76
,72,36,
,32,60,
,198,11

,133,
114,9
,201,
34,15
8,207
76,13
13,24
134,2
,169,
32,18
0,177
,169,
1,33,
112,0
65,32
4,165
118,0
,200,
,200,
,125,
112,0
34,14
,169,
,118,
,187,
7,48,
185,1
9,96

48,13
6,32,
13,24
7,124
,76,2
4,175
0,32,
11,13
255,1
0,187
,119,
0,44,
240,6
,201,
,255,
,32,9
,240,
134,1
134,1
2,169
,32,1
1,125
2,13,
0,240
127,3
3,169
4,13

3,52,
112,0
0,10,
,2,23
23,12
,173,
118,0
4,165
33,16
,76,2
201,1
169,3
,32,2
59,24
240,3
,241,
167,3
65,32
65,32
,58,1
92,24
,2,16
64,23
,219,
2,43,
,124,
3,120

169,7
,162,
224,2
2,169
6,169
123,2
,201,
,32,9
,173,
50,12
53,24
4,141
47,12
0,46,
2,118
32,72
2,112
,9,24
,9,24
41,12
1,141
9,58,
2,141
32,11
193,1
44,16
,104,

6,133

C,32,

50,24

,58,1

,0,13

,240,

59,24

,241,

123,2

6,140

0,10,

,123

7,76

32,24

,0,20

,241,

,0,20

1,76,

1,169

6,2,1

,124,

141,1

,64

2,0,3

33,70

9,123

133,1

,112

192

7,138

,122
201

1,59

,60

2
,132

19,96

7to32767 : reada :poke (i) ,a;next

MICRO

No. 57- February 1983

Samples of Command Use

PRINT@4,0;"string",a,b$

replaces

OPEN4,4,0:PRINT#4,"string",a,b$:
CL0SE4

INPUT@29,24;X

replaces

OPEN10,29,24:INPUT#10,X:CLOSE10

Idiosynciacies

While PRINT@3; will correctly
print to the screen, INPUT@0; may
not be used to input from the keyboard.
This aspect of the input was not con-
sidered important for instrument con-
trol, but it could probably be changed if
necessary.

PRINT!; requires that the user know
the correct listen or talk address. These

addresses may be formed by adding 32 or
64 to the device number. For example:

PRINT!36,0;65,66,13
PRINT!;67,68,13

will cause a printer device number 4
(listen address 36] to print A B (cr) and
then C D (cr). ASCD values 65,66,67,
68, 13 represent A,B,C,D, (cr) . Note that
the addresses are not sent in the second
command since the device has not been
unlistened and is still active on the bus.
The UNLISTEN is sent using
PRINT! 63; .

When you use the INPUT! com-
mand, remember first to send a talk ad-
dress using PRINT! (PA); and finally to
use PRINT!95; to send the UNTALK.

Mr. Priddle may be contacted at the
University of Toronto, Department of
Chemistry, Toronto, Canada M5S lAl.

IMCftO

70 INCOME 1AX PROGRAMS

(For Filing by April 15, 1983)

For APPLE 11/11* (DOS 3.3, 16-Sector)

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over.

5. Inputs can be checl(ed.

6. Inputs can be changed.

7. I. R.S. approved REVPROC
format.

8. Prints entire Form/Schedule.

9. Calculates Taxes, etc.

10. In 3.3 DOS, 16-Sector.

11. Fast calculations.

12. Use GREENBAR in triplicate
— don't change paper all
season!

13. Our 4th Year in Tax
Programs.

14. We back up our Programs!

Helpful programs to calculate and print the many Tax
Forms and Schedules. Ideal for the Tax Preparer,
C.P.A. and Individuals. For just $24.75 per disk, post-
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Programs are designed for easy-use, with check-
points to correct parts as needed. Results on screen
for checking before printing.

In all, there are more than 70 individual Tax Programs.
These include Form 1040, 1040A, 1040EZ, 1120,
1120S, 1041 and 1065. Also Schedules A, B, C, D, E,
F G, R, RP and SE. And, Forms 1116, 2106, 2119,
2210, 2440, 3468, 3903, 4255, 4562, 4797, 4835,
4972, 5695, 6251 and 6252.
And, vie have a disk m call "THE TAX PREPARER'S
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Announcing

THE GUIDE

A Complete Guide
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What's Where In the

APPLE?

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only $9.95*

The Guide provides full explanatory
text to lead you tlirougli tlie most
complete Apple memory map ever
published!

The Guide explains and
demonstrates how to use the atlas
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original volume!

MICRO makes It easy to order
Send check (payable to MICRO) to:

MICRO INK

P.O. Box 6502

Cholmsfom, MA 01824

Call our toll-free number:
1-800-345-8112

(In PA, 1-800-662-2444)

VISA and MasterCard accepted

*Add $2.00 sfiipping per book.
MA residents add 5%.

No. 57 - February 1983

MICRO

SSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSS®!*

tuin?u 5Ef\i5Ei:."'

VIC-20®
Personal Computer
RS232C Interface
Printer
Datasette
Disk Drive
Expansion Module
Joystick
Game Paddles
Telephone Modem
Terminal 40
Produces 40 column output o( information received through the modem

VIC-1210 VIC 3K Memory Expander Cartridge

Plugs directly into the VIC'S expansion port. Expands to 8K RAM total.
VIC-1110 VIC 8K Memory Expander Cartridge

8K RAM expansion cartridge plugs directly into trie VIC.

VIC-1011A RS232C Terminal Interface

Provides mtertace between the VIC-20 and RS232 telecommunications
Connects to VIC'S user port

VIC-20®

VIC-1011A

VIC-1515

VIC-1530

VIC-1540

VIC-1010

VIC-1311

VIC-1312

VIC-1600

CM-151

CM
CM

16K Memory Expander
24K Memory Expander

179.95
39.95

334.95
67.50

349.95

139.95

9.95

19.95

99.95

29.95

34.95

52.50

39.95

modems-

89.95
110.95

CARDBOARD 6 $87.95

An expansion mtertace for the VIC-20 Allows expansion to 40K or accepts up to six

games. May be daisy chained for more versatility.

CARDBOARD 3 $29 95

Economy expansion interface for trie VIC-20.

CARD "? " CARD/PRINT $79 95

Universal Centronics Parallel Printer Interface for the VIC-20 or CBM-64 Use an

Epson MX-80 or OKIOATA or TANDY or just about any other

CARDETTE $39 95

Use any standard cassette player/recorder with your VIC-20 or CBM-64.
CARDRITER $29.95

A light pen with six good programs to use with your VIC-20 or CBM-64

BUSINESS &HOMEAPPLICATIONS FOR VIC-20®

CW-107A Home Calculation Program Pack

CPV-31 Data Files - your storage is unlimited

CPV-96 Household Finance Package - to keep records of aii

your household expenses
CPV-208 Bar-Chart - display your numerical data
CH Turtle Graphics - team programming
CH VIC Forth - is a powerful language lor BASIC programming
CH HES MON - is a 6502 machine language monitor with

a mini-assembler
CH HES Writer - time-saving word processing tool
CH Encoder - keep your personal records away from prying eyes
CT-21 Statistics SadiStiCS - statistical analysis
CT-1 21 Total Time Manager 2.0 - creates personal or

business schedules
CT-1 24 TotI Label - a mailing list and label program
CT-1 25 Tott Text BASIC

CT-1 26 Research Assistant - keep track of reference data
CT- 1 40 TotI Text Enhanced

CM-152 Grafix Designer - design graphic characters
CQ-5 Mlnjmon - allows you to program, load, save, or execute
machine language programs

CT-3 Order Tracker

CT-4 Business Inventory - to maintain record of inventory

CPV-210 Bidder

CPV-217 Cash Flow Model - determine cash flow

CPV-220 Client Tickler

CPV-221 Club Lister

CPV-224 Depredator

CPV-236 Investment Analyst - keep track ol investments
and investment opportunitites

Present Value
Super Broker

Syndlcator - calculates whether to buy or sell
Ticker Tape - maintains investments profile

Un-Word Processor - screen editor

Phone Directory - never lose a phone number again
Checkbook - home utility" program
Calendar My Appointments - print a calendar

for every month in any year

The Budgeter - place your personal finances in order
HESCOM - transfers data and programs bidirection-
aliy between VICs at three times the speed of a disk drive
HESCOUNT - monitors program execution
HESPLOT - Hi-res graphics subroutines
Conversions - figures, volume, length, weight, area,
and velocity to all possible configurations
The Mail - your complete mail program Cassette

Disk

Home Inventory - lists your home belongings

Check Minder - (V-20 & 64)

keep your checkbook the right way
CS General Ledger - a complete general ledger

CPV-251

CPV-269

CPV-270

CPV-274

CPV-276

CPV-286

CS-111

CPV-294

CPV-296
CPV-327

CPV-328

CHV

CPV-367

CS
CS

$48.95
14.95
30.95

8.95
34.95
49.95
34.95

34.95
34.95
14.95
15.95

13.95
15.95
17.50
29.95
12.95
13.95

15.95
15.95
13.95
12.95
16.95
13.95
9.95
12.95

10.95
12.95
13.95
14.95
16.95
9.95
14.95
14.95

12.95
40.95

19.95

12.95

7.95

24.95
29.95
17.95
14.95

19.95

BUSINESS & HOME APPLICATIONS FOR C-64

CHC-504 HES Writer - word processor $39.95

CHC-503 Turtle Graphics II - utilizes the full graphics of your 64 49.95

CHC-502 HESMON - machine language monitor w/mini-assembler 34.95

CHP-102 6502 Professional Development System 29.95

CFG Data Files - a management program 27.95

MANY MORE PROGRAMS FOR YOUR 64 & 20

COMMODORE SOFTWARE

VIC-1211A VIC-20 Super Expander $57 99

Everything Commodore could pack into one cartridge - 3K RAM memory expansion,
high resolution graphics plotting, color, paint and sound commands. Graphic, text
multicolor and music modes. 1024x1024 dot screen plotting All commands may be
typed as new BASIC commands or accessed by hitting one of the VICs special
function keys. Includes tutorial instruction book Excellent for all programming levels
VIC-1212 Programmer's Aid Cartridge $45.99

More than 20 new BASIC commands help new and experienced programmers
renumber, trace and edit BASIC programs Trace any program line-by-line as it
executes, pause to edit. Special KEY command lets programmers redefine function
keys as BASIC commands, subroutines or new commands
VIC-1213 VICMON Machine Language Monitor $48 99

Helps machine code programmers write fast efficient 6502 a:^sembly language
programs Includes one line assembler/disassembler

GAMES FOR YOUR VIC-20®
Cribbage
Motor Mouse

Avenger Cart. - an invasion of space intruders
and you're the VIC "Avenger"

Superstot Cart. - great music and sound effects!
Super Alien Cart. - you re trapped in a maze
Jupiter Lander Cart. - pilot your "Jupiter Lander"

Draw Poker Cart.

Midnight Drive Cart. - authentic night driving

Radar Rat Race

Sky Falling

Mole Attack - a colorful 'cartoon action" game

Raid on Ft. Knox - try to escape the guards

Adventure Land - Formerly available only on larger,

more expensive computers. All Adventure games are decoded tc

"talk" on the Type N Talk voice synthesizer (available from VOTRAX)

Pirate Cove Adventure - yo. ho. ho. & a bottle of rum 31 .95
Mission Impossible Adventure

The Count Adventure - trapped in Dracula s castle
with 3 days to find and destroy the vampire
CW-1918 Voodoo Castle Adventure - you have to free
Count Yorga from a curse

Sargon II Chess - seven challenging play levels
Gorf - (The smash-hit arcade game!)
Omega Race - the ultimate space game
SeaWOlf — an explosive Bally Midway arcade 'classic
Maze of Mikor - adventure-packed game with
stunning graphics

Tank Wars
Pinball

Simon - it gets tougher as you get better Great for

kids of all ages

Fuel Pirates

Laser Blitz

Tank Trap

Concentration

Dam Bomber - pilot your plane, avoid enemy fire
ShamUS - search room after room for the shadow-
eluding androids, two levels of intense arcade action

Protector
Breakout

Hangman - unbelievable graphics and sound

Memory - vie challenges your memory

Match - hand and eye coordination

Monks - a devilish game of logic
Bomber - you must decide who you want to fly for.
then pick a target and your experience level
Amok - the halls of Amok are populated by robots that
obey one instruction - get the intruder
Tank vs. UFO - the tank is moving back and forth
along the base, shoot the UFO before it shoots you
Snakman - Pacman for the VIC
Defender on Tri - you're the pilot of the experimental ship. Defender
3-D Man - the popular arcade game, requires 3K

Exterminator - a game luii of bugs

CCS
CCD
CW-1901

CW-1904
CW-1906
CW-1907
CW-1908
CW-1909
CW-1910
CW-1911
CW-1912
CW-1913
CW-1914

CW-1915
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MICRO

No. 57 - February 198:

VIC RS-232 Printer

by Michael V. Tulloch

The hardware and software
needed to interface RS-232
devices to Commodore's ViC
computer are described. A Radio
Shacl( Line Printer VII is used as
an example. Other examples
include hardware to convert
RS-232 voltages to TTL, a BASIC
program to convert hex code
data to POKES, a machine-
language printer driver, and a
discussion on using a CTS line
from VIC.

Printer Driver

requires:

VIC-20

RS-232 printer
hardware interface

The Piogiammeis Refeience Guide
(PRG) is indispensable for understand-
ing the VIC'S RS-232 implementation.
Unfortunately, some of the informa-
tion is misleading.

Part of PRG's chapter four is
devoted to the RS-232 interface.
Although quite versatile, VIC software
does not implement two RS-232 func-
tions that may be important with many
printers. Neither "ring indicator" (RI)
nor "clear to send" (CTS) is included.

Unless a printer has a large buffer to
allow simultaneous data input while
printing, some handshaking is re-
quired. The simplest approach involves
waiting long enough after each output
to the printer to be sure the printer has
received, printed, and returned the print
head. In BASIC this is easily done; from
the command mode it is not.

Standard printer handshaking in-
volves one line. While it is busy, the
printer sends out a signal on this line.
The computer reads this busy line and
holds off further output until the
printer is free. A busy line usually con-

nects to RS-232 CTS ~ not used by
VIC'S software.

After referring to the VIC PRG and
considerable experimentation, I deter-
mined the only way to use the CTS line
was to write a program to read it directly.

Hardware

Another problem, caused by VIC's
non-standard version of RS-232, in-
volves voltage levels. VIC outputs to
+ S volts — TTL levels. VIC also ex-
pects to -(- 5 volts for any inputs. You
must observe these limitations since
the RS-232 lines connect directly to a
6522 VIA. Because RS-232 standard de-
vices expect to be sent ±12 volts and
usually output the same voltage range,
there is an obvious incompatibility.

The circuit shown in figure 1 adjusts
voltage levels. It converts VIC's 5-volt
signal to ± 12 volts [actually ± 10 volts
— OK for most applications) and vice
vetsa. Although, there are several ways
to accomplish this conversion, the ap-
proach chosen is capable of isolating

the VIC completely from the printer if
the printer supplies the ±12 volts or a
separate ± 12-volt supply is used.

A 74LS04 hex inverter protects the
input and output lines of the RS-232
port. This inverter also corrects VIC's
signal inversion problem. An opto-
isolator shifts the level from 0-5 volts
to ± 12 volts.

In this example a single rectifier and
electrolytic capacitor converts VIC's
±9-volt ac output to about ±12 volts
dc. A resistor divider provides a ground
for the printer. Since RS-232 inputs
draw very little current, this circuit
works adequately. Note that the pro-
tective ground and signal ground of the
VIC are at the same potential and are
not isolated. Do not connect either to
the printer ground.

The pin connections shown in
figure 1 are for the Radio Shack printer.
Note that Radio Shack calls the busy
line the 'STATUS' line. Any three-wire
cable will do. if you have an RFI prob-
lem (and to comply with the new rules

Figure 1

R/S Printer

AV +

VIC Parallel
User Port

DATA

IC1 Power;
Pin 7GND
Pin 14+5

-12V tL 47 p

DC T 35V. 11

VICGND
CB2 data out

9V AC

No. 57 - February 1983

MICRO

for Part B computers) use a shielded
cable. Connect the shield either to the
printer ground or VIC's protective
ground {not both!].

As an aid to trouble shooting, I in-
cluded a couple of LEDs. Although they
increase the cunent required by the cir-
cuit, they may be helpful in diagnosing
interfacing problems. Besides, I enjoy
watching them blink as VIC talks on
the RS-232 port.

Although rather primitive, the in-
terface can be constructed out of junk
box parts. It's so cheap that even if you
buy all new parts in five packs at Radio
Shack, the bill will come to only
$12.00 (see table 1|.

VIC uses a 6522 VIA (versatile inter-
face adapter) for the RS-232 port. The
same chip also drives the user port.
Although VIC has two VIAs, we're in-
terested in chip #1. Memory addresses
$9119-$911F (37136-37151) access this
chip. The RS-232 software sets all the
control registers. Therefore we won't
have to do it and I'll ignore the process.
As I've mentioned, however, the CTS
line is not read by the RS-232 software.
This line is tied to PB6 [pin K). PB6 is
one of eight data lines of the B VIA port
I/O register. The B port register can be

Table 1: Parts List

Cost

iliUsed

Item

Radio Shack Part #

$ 1.98

Opto- isolators

276-1628'

0.79

74LS04 Hex Inverter

276-1904

1.19

LEDs

276-032

0.39

6.8K Resistor 14 W

271-1333

0.39

IK Resistor WW

271-1321

0.10

56 OHM Resistor

[Assortment)

0.49

1N4001 Diode

276-1101

0.69

47 F 35V Electrolytic

272-1015 or 272-1026

2.99

Edge Connector
(Cut to 24 pins)

276-150 or 276-151

1.49

4-Pin DIN Plug

Available some stores

1.29

14-Pin DIP Socket
3-Wire and 6-Wire Cable

276-1993

$11.79 (pi

us tax) tota

•This part has been discontinued by Radio Shack and

may not be available in

all stores.

Nearly any

opto-isolator will do.

read or written to at memory address
$9110 (37136).

Normally all VIA pins are either
defined as outputs or pulled up to 5
volts. PEEKing the port register should
yield a value of 255. In other words, all
pins (outputs and -i-5 volts) are seen as
logical 1. If pin K is connected to the

printer's 'busy' line so that the busy
condition pulls the line to volts, then
PEEKing $9110 will return a value of
191 when the printer is busy. To recog-
nize a busy printer you could read the B
port and look for a value of 191.
Printer Driver Software

As Murphy would have it, things

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MICRO

No. 57 ■ February 1983

aren't entirely that simple. VTC, both
too smart and too dumb, has a 512-byte
RS-232 buffer. When printing to the
RS-232 port, characters go first to the
buffer. If you don't print more than 512
characters, the program will continue
running without waiting for the
printer. The RS-232 software sends
characters out simultaneously with
other VIC functions (except serial port
and cassette).

The "too dumb" part involves
VIC's failure to use the CTS line. In-
stead you have to handle the busy line
yourself. My solution to this problem
gives up the advantages of the printing
buffer. The machine-language program
described here only allows characters
to be output to the buffer at print speed.
It holds up printing to the buffer while
the printer returns its print head. This
slows down RS-232 communications
considerably, but it works.

To intercept the characters as they
are printed to the buffer, the output
vector at $0326-$0327 (806-807) must
be changed. For the routine used here
they must be changed to point to the
cassette buffer $033C (828) where our
machine-language program lives. This
vector can be changed either from
BASIC or the keyboard.

POKE 806,60 lo byte
POKE 807,03 hi byte

Once you have built the interface
and an appropriate cable, the next step
is to interface the software — not a sim-
ple task. Since I don't have a VIC
machine- language monitor, I used an
assembler on my Apple. Listing 1 is the
resulting assembly code. Liberal com-
ments are provided, so I'll only briefly
describe the routine. Two delay loops
are used. The first loop checks the CTS
bit until $8F successive checks show it
has gone high, which means the printer
is not busy. The second delay executes
if the last character printed was a car-
riage return. These two delays assure
that spaces between characters are not
misinterpreted and that the routine
sees the print head return to home.

Because the listed version uses four
locations at the top of the VIC's screen,
you can watch the characters pass to
the printer and the various timing loops
perform. The comment section at the
top of the listing suggests alternative
storage locations for permanent use.
Don't worry about the screen scrolling
— the routine is not affected.

Listing 1

£.

VIC

OUTPUT ROUTINE FOR RS-

-232 *

%^\I2.

:*:

MICHAEL TULLOCH

17 AUG 82

TH.TS ROUTINE USES THE

CTS *

LINE WHICH

IS NOT IMPLIMENTEO*

THE VIC

SOFTWARE.

NOTES ■■

DIFFERENT PRINTERS MAY *

REQUIRE

DIFFERENT

CNTR *

VALUES.

DIFFERENT DELAY VALUES *

MAY BE

NEEDED.

LOCATIONS OF SAVA

SAVX.. *

FLAG, AND DELAY COUNTER *

MAY BE

CHANCED TO

SAVA EQU *0380 *

SAVX EQU *03ai »

FLAG EQU *03S2 *

DCNTR EQU *0383 *

32
33
34

«****«****«************«*»*»*»**

ORG

«033C

36
37
38

*
*
SF

THIS IS THE START OF

THE CASSETTE BUFFER

EQU

«lE0e

SAVE ACCUMULATOR

FLAG

EQU

*1E02

FLAG FOR CR AS LAST CHARACTER

OUT

EQU

«F27A

REAL CHARACTER OUTPUT

SfiVX

EQU

*1E01

SAVE X REGISTER

CNTR

EQU

«8F

EMPIRICAL DELAY BETWEEN SPACES

OCNTR

EQU

«1E01

BPORT

EQU

*9110

LOCATION OF RS232 CTS REGISTER

B33C

STA

SAVA

SAVE ACCUMULATOR

easF

STX

SAVX

SAVE X REGISTER

0342

flD

LDfl

FLAG

GET THE FLAG

P345

CMP

*13

WAS IT CR

9347

BEQ

DELAY

IF SO THEN WAIT A WHILE

a349

LDA

NO SO RESET FLAG

034B

STA

FLAG

TO ZERO

e34E

1=16

RESET

LDX

CNTR

SET UP NUMBER OF TIMES TO LOOK

a350

flO

LOOK

LDA

BPORT

GET THE CTS SIGNAL

0353

CMP

#191

IS IT LOW?

0355

BED

RESET

YES SO START LOOKING ALL OVER

0357

DEX

SO DECRIMENT NUMBER OF LOOKS

035S

BNE

LOOK

TAKE ANOTHER LOOK

FINALLY, ALL LOOKS GOOD

tS35(=l

FID

LDA

SAVA

SO.. RESTORE ACCUMULATOR

eo5D

LDX

SAVX

RESTORE X REGISTER

0368

CMP

#13

IS OUTPUT VALUE A CR?

0362

FI3

BEQ

FLAGSET

YES, SO SET FLAG

0364

64
65

:*:

JMP

OUT

NO SO OUTPUT THE CHARACTER
DON'T COME BACK

0367

FLAGS

ET STA

FLAG

SET CR FLAG TO 13 < *0D )

03iSB

JMP

OUT

SET, SO OUTPUT THE CHARACTER,
DON'T COME BACK

13360

fl3

DELAY

LDA

««FF

MAKE IT A LONG DELAY

a36F

STA

OCNTR

SAVE ACCUMULATOR AT TOP OF SCREEN

0372

fl2

TRT

LDX

«*FF

MAKE IT A REALLY LONG DELAY

0374

Cfl

XDEC

OEX

START

COUNTING OUT

0375

73
74

ONE

XDEC

IF X IS NOT ZERO THEN
DECRIMENT SOME MORE

0377

DEC

DCNTR

DECRIMENT THE OUTSIDE COUNTER

037fl

BNE

XSTRT

IF NOT 00 INNER LOOP AGAIN

e37C

JMP

«0349

DONE AT LAST RETURN FROM DELAY

To make entering the machine-lan-
guage program easier I wrote the BASIC
program in listing 2. Note that the data
statements contain the code in hex.
The program reads the hex data and
converts it into decimal numbers. It
also reads the start address from a data
statement, then POKEs the data into
successive memory locations. By re-
moving lines 150 and 160 and changing
the data in lines 5-17, this program will
convert and enter any hex code se-
quence. For those of you who don't
have VICMon, this is easier than con-

verting hex to decimal and typing it in
as data or typing a lot of POKEs.

Using the programs is easy; just
follow these instructions:

1. Enter the BASIC program.

2. SAVE the BASIC program.

3. RUN the BASIC program.

4. Either from the keyboard or from
within a program,

OPEN2,2,3,CHR$(7) + CHR$(0)

5. To LIST to an RS-232 printer
CMD2

No. 57 - February 1983

MICRO

Listing 2

I GOTO lee

5 DHTH 828' REM START OF CHSETTE SUFFER
9 REM.

9 REM MfiCHINE LflNCUHCE PROGRAM FIS HEX DflTfl

10 DHTH 8D,02,lE,8E-01.1E.HD,02,lE,C3<0D.F0,24,H9,0e

II DHTfl 8D.02,lE.H6;8F.HD,lB,91.C9,BF,F0,F7,Cfl,DB,F6

12 DHTfi FiD.00-lE,HE.ai.lE,C9,0D/F0.03.4C.7H.F2/SD-02.1E..4C.7H,F2.Fl9,FF,8D.04.1E

13 DflTfl fl2-FF,CFI,Da,FD.CE.a4,lE.D0,F6.4C.49,03

17 DHTH END

18 REM ***** END DFITFI *****

19 REM HEX TO DECIMAL SUBROUTINE

20 READ M'lF Fi«-"END" THEN 98

25 IF LEN<Fi«>»lTHEN 40 : REM JUST ONE BIT SO SKIP HI BIT STUFF

30 fil*»LEFT*<fl*, D'COSUe S0'H»VflL<fil*)'REM DO HI BIT

40 H1*»RICHT«<FI«,1)-G0SUB e0'S=VFIL<Fll«>-REM DO LO BIT

50 V«<fl*16>+B'REM MAKE IT BASE TEN

70 fl"0-B-a'REM KEP IT CLEAN

75 RETURN

79 REM CHANCE LETTERS TO NUMBERS SUBROUTINE

80 IF VAL<A1*>>0 THEN RETURN 'REM IT IS A NUMBER

82 IF A1«»"0" THEN RETURN ' REM IT IS A ZERO

83 REM IT WASN'T A NUMBER SO IT MUST BE A LETTER

84 Z»ASC<A1«)' REM CHANGE TO A NUMBER

86 A1«"STR«<Z-55>'REM MAKE NUMBER 10 TO 15
90 REM A NEAT TRICK TO CONVERT A-F TO 10-15

98 RETURN

99 REM ************* MAIN *************

100 REM POKE THE MACHINE LANGUAGE

110 READ S'REM GET THE STARTING MEMORY LOCATION

120 GOSUB 20' REM CHANCE HEX TO BASE TEN

130 POKE S,V'REM DO IT

135 PRINTS/ViREM SO WE CAN SEE IT

137 S-S+1'REM INCRIMENT THE MEMORY LOCATION

138 V=0

140 IF A«<>"END" THEN 120

150 P0KE36e79.8'REM MAKE SCREEN BLACK SO WE CRN SEE IT WORK

160 POKE 306,6e'POKEe07,03'REM SET THE OUT PUT VECTOR TO ROUTINE

190 END

LIST

PRINT#2

CLOSE 2

RUN/STOP - RESTORE
Remember to PRINT# before
CLOSEing the RS-232 channel. If the
busy line goes low and stays there, the
system will hang. If you unsuccessfully
try to run/ Stop-restore, you may have a
printer problem. Good luck and happy
PRINT#ing!

References

1. Butterfield, J. and Law, Jim, Com-
pute!, Vol. 4, No. 8, August 1982,
p. 99.

2. Finkel, A., et. al., Piogiammei' s
Reference Guide, Commodore Busi-
ness Machines, 1982.

3. Lesea, A. and Zaks, R., Micio-
pwcessoT Inteifacing Techniques,
Sybex, Berkeley, CA, 1977.

Michael Tulloch is a consultant in
engineering psychology and president of
Intelligent Home Systems, Inc. He may be
contacted at Intelligent Home Systems,
Inc., P.O. Box 0858, Roswell, GA 30077.

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No. 57 - February 1983

MICRO

PROM BASIC for the C I P

by David A. Jones

This article describes a unique
way to increase the performance
of the Superboard II/C1P without
a disl( interface and drive. The
modifications are for the user
who wishes to dedicate his
system to oniy a few specific
tasi(S that are run often, or who
is Inexperienced in the use of
sophisticated computers.

PROI\A BASIC

requires:

C1P

As an alternative to upgrading a
cassette-based system to disk where
improved performance is attained at a
considerable price, I would like to share
my ideas on a PROM BASIC system.
Even with the general decline of com-
puter hardware prices, adding a disk to
my CIP would cost twice the original
investment. The alternative I refer to is
EPROMs. 2732 EPROMs are available
for approximately $10 apiece, so for
less than $100 you can buy eight
EPROMs, a 24-pin ZIP connector, a
couple of 74LS139 decoders, and still
have enough left over to pay the sales tax.

There have been several articles in
MICRO (39:97 and 45:31, for example)
to expand the 600 board via the Jl con-
nector. I won't go into detail here ex-
cept to say I limited my memory ex-
pansion to 24-pin devices. The byte-
wide RAM parts are now more cost ef-
fective than 2114's when you consider
the price of sockets and power dissipa-
tion, and they have the added advan-
tage of being pin-compatible with 2716
and 2732 EPROMs.

An expansion board with eight
24-pin sockets will utilize all of the
generally available unused memory in
the 600 board if populated with 2732
EPROMs, or half of that amount if

Listing 1

0000

;8UT0B8SIC,

II -2-31

0000

;ev

08VI0 8

. JONES

0000

97R0

*=$9788

97fi0

VTMF

=*F8

97ft8

800R

=$FC

9780

VTNF

=$FE

97fi0

XTMF

=*FF

97fi0

IVEC

=i02IS

100

S7m

WftRM =$8274

110

97a0

LEG8L =$FE93

120

97FI0

R0L8 =*FE08

130

97m

INPUT =*FEEO

148

97B0

B8S0UT=tFFEE

150

97fi0

;

160

97FI0

R92fl

L08

#-*

FRONPT

170

97ft2

20EEFF

JSR

B8S0UT

180

97fi5

8204

LPX

»4

190

9787

20EOFE

INNN

JSR

INPUT

GET 800RESS <4 HEX OIGITS)

200

97aft

20EEFF

JSR

B850UT

210

97FI0

2093FE

JSR

LE(j8L

HEX CHRR8CTER ?

220

97B0

86FF

STK

XTMP

230

97B2

8200

LOX

240

97B4

20O8FE

JSR

R0L8

ROLL IT INTO 800RESS REGIS

258

97B7

mFF

LOX

XTHP

268

97B9

Cfl

OEX

270

97Bft

O0EB

BNE

INNN

GET REST OF 800RESS

280

97BC

;

298

97BC

801802

L08

IVEC

S8VE INPUT VECTOR

308

97BF

S5F8

ST8

VTtlP

310

97C 1

801902

L08

IVEC+I

320

97C4

85FB

ST8

VTMP+I

330

97C6

348

97C6

R00897

L08

MOVE+ 1

SET INPUT VECTOR

350

97C9

801802

ST8

IVEC

368

97CC

8D0B97

L08

nOVE+2

370

97CF

801902

S18

IVEC+I

380

97P2

8080

LOV

#(3

398

9704

S4FE

STV

VTftP

PRESET V REGISTER

480

97D6

;

418

9706

4C7482

JNP

U8RI1

428

9709

430

9709

440

9709

4C0C97

MOVE

JHP

L080

458

970C

84FE

L080

LOV

VTNP

LORO PROGRRM FROM PRO/1

468

970E

BIFC

L08

(800R),

478

97E0

C999

CMP

#$99

ENO OF FILE ?

480

97E2

F008

BEQ

OUT

490

97 E4

INV

500

97E5

S4FE

STV

VTMP

518

97E7

0002

BNE

RETN

520

97E9

E6F0

INC

800R+ 1

NEXT BLOCK

538

97 EB

RETN

RTS

540

97EC

;

550

97 EC

85F8

OUT

L08

VTNP

RESET VECTOR

560

97EE

8DI802

ST8

IVEC

570

97FI

85FB

L08

VTtlP* 1

580

97F3

SO 1902

ST8

IVEC+I

590

97F6

,,'

680

97F6

4C7482

JMP

H8RM

618

97F9

;

(continued)

MICRO

No. 57 - February 1983

HM6116 or TMM2016 RAMs are used.
I chose a mixture of 4K RAM and 24K
EPROM, which works well for a
cassette-based system.

I originally built my expansion in-
terface to house the Assembler/Editor
and Extended Monitor in EPROM so
they always would be available im-
mediately. I wired in extra sockets so I
could do the same with some
assembly-language games for my
children. I figured if video games have
programs in cartridge packs so can my
CI P. The Assembler and Extended
Monitor are now as accessible as ROM
BASIC. The Extended Monitor can be
run directly from PROM, but since the
Assembler/ Editor has self-modifying
code it must be moved to RAM to run. I
wrote a short routine to do this
automatically when I call the program.
The response is instantaneous.

The next logical question was, if I
can do it with machine-language pro-
grams, why not BASIC programs also?
Some obvious answers are that BASIC
programs are stored in token form, they
tend to occupy more memory, they de-
pend upon pointers in page zero that are
set when the program is loaded, and
these pointers are modified as the pro-
gram runs. None of these reasons seemed
insurmountable, although they were
not without challenge.

I tried storing page zero along with
the tokenized program and then load-
ing both into RAM when I wanted the
program. A problem occurred since my
storing and loading routines also used
page zero and therefore modified what I
wanted to save. Also, storing page zero
required 256 more bytes of storage and
more complicated code to handle it
unless page two and three were stored,
which used still more space.

This method worked, but I decided
to try another tack — emulating a load
from the serial port. The advantage of
this procedure is that you don't have to
use page zero and the application pro-
gram can be stored in ASCII rather than
token form. Two or more programs can
be chained, or program and data can be
loaded independently. My word pro-
cessor is in BASIC so I must retain this
capability. The disadvantage is that
ASCII takes more storage space. How-
ever, for moderate sized programs I find
not storing page zero makes the trade-
off acceptable.

To load a program from EPROM, a
three-part machine-language routine
(listing 1) is called from BASIC via the

Listing 2

16 eciee

i STORE, l-l

-82

2d eeee

iBV

ORVID R

. JONES

30 9600

*=$9600

40 9600

50 9600

flENC

=$86

END OF MEMORV.. HIGH ADDRESS BVTE

60 9600

STOH

=$F0

STORE POINTER.. 2 LOCATIONS

70 9600

VTMF =$FE

TEMPORFIRV STORE FOR V REGISTBR

S0 9600

LFLG =$020

3 BFISIC LORD FLFIG

90 9600

FLAG =$0390 mOE FLAG

100 9600

BFISIN =$FFEB INPUT ROUTINE

1 10 9600

BftSOUT=$FFEE OUTPUT ROUTINE

120 9600

130 9600

H003

5ETP

LOV

#$03

SET STORE POINTER

140 9602

S4FI

STV

STOR+I

150 9604

H000

LDV

160 9606

S4F0

STV

STOR

170 960S

tS0 960S

20EBFF

CHECK

JSR

BFISIN

GET CHFiR FROM KEVBORRD

190 960B

C94C

CMP

#'L

CHECK FOR L TO SWRT LORD

200 960D

D0F9

BNE

CHECK

IF NOT KEEP LOOPING

2(0 960F

SO90O3

5TR

FLFIG

DISPLRV FLRG

220 9612

l^9FF

LOR

#$FF

230 9614

SD0302

STB

LFLG

SET BRSIC LORD FLRG

240 9617

250 9617

20EBFF

JSR

Bi^SIN

GET CHRP FROM RCIR

260 96 m

C900

CMP

DON'T STORE NULLS

270 96 IC

F0F9

BEO

2S0 96 IE

20EEFF

JSR

BRSOUT

DISPLRV CHRRRCTER ON CRT

290 9621

S4FE

STV

VTMP

SRVE V

300 9623

R000

LOV

310 9625

9IF0

STFI

<STOR>,

V STORE CHRRRCTER

320 9627

E6Fe

INC

STOR

330 9629

D008

BNE

RETN

340 962B

E6FI

INC

STOR+I

INCREMENT BLOCK IN MEMORV

350 9620

R5FI

LOft

STOR+I

360 962F

C5S6

ChP

MENC'

END OF MEMORV ?

370 9631

F005

BEQ

OVER

3S0 9633

R4FE

RETN

LOV

VTMP

RECRLL V

390 9635

4CI796

JMP

GET NEXT CHRRRCTER

400 9638

;

410 963S

ft94F

OVER

LDFI

#'0

OISFLRV OVERFLOW FLRG

420 963R

SO90O3

S7fl

FLAG

ON 25TH LINE

430 96 3D

20EBFF

JSR

BRSIN

GET NEXT CHRRRCTER

440 9640

S09203

S7fl

FLfiG+2

DISPLRV ON 25TH LINE ONLV

450 9643

4C3S96

JMP

OVER

LOOP UNTIL BRERK

460 9646

USR(X) function. POKE 11,160:POKE
12,151:X = USR|X) for the addresses in
listing 1. Once called, this routine
changes the input vector to point to the
second part of the routine. The second
part feeds data to the BASIC load rou-
tine just as if it were coming from the
serial port or keyboard. A check is
made to see if the data contains a $99,
which indicates the end of the load and,
if so, the input vectors are reset to their
original value by part 3. Then it jumps
back to BASIC warm start. This routine
allows the stored program to be located
anywhere in memory and prompts the
user with an asterisk ('). The user
responds with the starting address.

Storing the program in EPROM is
more complicated but by no means dif-
ficult once you imderstand the concept.
Also, you must have access to an
EPROM programmer.

First, be sure the program to be
stored is thoroughly debugged and user
friendly. Remove REM statements and,
if you want, pack code to save memory.

Save the resulting code on cassette tape
and load the program back into mem-
ory with the routine in listing 2. The
file is now stored in a straight ASCII
format with no tokens. Find the end of
the file, delete the OK, and insert a $99.
The last available RAM location is
stored by BASIC cold start in locations
$85 and $86. When storing, the routine
checks for the end of RAM and displays
the overflow flag if the end is reached.
No more loading occurs but all further
incoming data is displayed on the 25th
line. Depressing the space bar ter-
minates cassette input and reverts back
to the keyboard for input. Anything
typed now will be stored in the next
location. At this point you should
break to the monitor and call your
EPROM loading routine. I use my
smart terminal program to perform the
storage function, but since the hooks
are unique to my system, I mention
only the following: transfer the
memory image to your EPROM pro-
grammer and program the EPROM. I do

No. 57 - February 1983

MICRO

this with my machine-code file-save
routine. This often is called the OSI
checksum format but is really the MOS
Technology Binary Loader, which is
recognized by many commercial PROM
programmers. The OSI Extended Moni-
tor calls this the SAVE routine.

You may wonder why you should
go to all this trouble when a disk offers
more versatility. Some reasons are:
cost, speed (a 3K BASIC program takes
3 minutes and 14 seconds — EPROM
takes 13 seconds], ease of operation for
novice users, absence of mechanical
transports, the fact that the program is
generally crashproof and quickly re-
covers if a crash occurs, and the need
for less desk space and interface cables.

Some of the programs I find useful
to have in EPROM (in addition to
games) are a renumber utility, a word
processor, a stock market monitor with
a cassette data base that I update each
week, and brief programs I might want
on short notice. I installed a ZIP con-
nector at location $4000 to facilitate
changing PROMs.

You could, of course, have a com-
pletely dedicated system with PROMs

as the only mass storage media. Such a
system could be used in a process con-
trol environment or office that con-
stantly uses the same set of programs
day after day with no changes. The
system could be programmed to boot
and call a menu on power up. Changing
the output vector to load the program
without displaying it would speed up
the loading process by about 50% —
three or four seconds versus seven or
eight seconds for a 4K program — and
would be more asthetically pleasing to
a non-computer professional.

For the do-it-yourselfer, three
sources of EPROM programmer kits are
listed here:

1. Micro Technical Products, Mesa,
Arizona, $45.00 - kit, $15.00 - bare
board, documentation and software.

2. John Bell Engineering, Redwood
City, California, $39.95 - kit, $24.95
- bare board only.

3. Aardvark Technical Services, Walled
Lake, Michigan, $75.00 - assembled
and tested, $24.95 - bare board only.

Although the Aardvark board is the
most expensive, it is designed
specifically for the 600 board. The John

Bell board is for the Apple but can be
coaxed to work with any 6502 system.
The Micro Tech unit is a general-
purpose board and is the one I ordered.

Other Methods

You can double the ROM/PROM
capacity of the 600 board with or with-
out the Jl connector. BASIC-in-ROM is
stored in four 2316's which are 2K by
8-bit 24-pin ROMs in U9, UIO, Ull,
and U12. Replacing these with 4K by
8-bit 2732 EPROMs doubles the storage
capacity for a total of 16K available at
these physical locations. The extra ad-
dress decoding needed to support the
additional 8K of EPROM requires only
one 74LS139 IC and can be installed in
one of the proto locations.

Assigning addresses $8000-$9FFF to
the newly installed memory works
well with existing usage and minimizes
the possibility of conflict if you decide
to add the 610 board later. BASIC-in-
ROM starts at $A000; i.e., $9FFF-(- 1.

Now that you have this extra
memory available, how can you use it
to best advantage? Relocating the Ex-
tended Monitor to $9800-$9FFF keeps

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Box 50 • 291 Huntington Ave. Boston 02115

MICRO

No. 57 • February 198;

it out of the user memory area and
allows it to co-reside with the Assem-
bler/Editor, increasing its usefulness.
You can now jump back and forth be-
tween the Extended Monitor and the
Assembler/Editor at will without
reloading either program or source
code. This makes debugging easy.

Since the original Extended Monitor
resides in memory from $0800-$0FFF,
the offset is exactly $9000, simplifying
cross references to the original. A table
located at $0960-$0999 is used to
decode the monitor command and
jumps to the selected routine. When
you relocate the code, this table must
be modified manually by adding the
offset to every odd location within the
table; i.e., $B30B becomes $B39B —
the new jump address for the 'A' com-
mand at $0962,0963. The Monitor is
now entered at $9800 and no user RAM
is employed (page zero excepted).

I located the Assembler/Editor
storage from $8040 to $9191. The
Assembler/Editor uses self-modifying
code and must be resident in RAM
memory to run. I use the routine in
listing 3 to move the code to its original
location. Note that none of the text
storage area ($1391 and up] is written
to during the move, so recovery from

Listing

Id eeee

jRSSEMBLER

CRLL, 11-15-81

20 0000

J By

DRV ID h

. JONES

30 0000

:REL0CRTE5

COLE STORED IN ROM TO RRN

40 0000

50 8000

*=$S000

60 S000

FRHl

=$80

FROM HODRESS, HIGH BVTE

70 8000

FRLC

=#40

FROM RDORESS, LOU BVTE

S0 S000

TOHl

=#02

TO RODRESS, HIGH BVTE

SB 8000

TOLC

=$40

W RDORESS, LOU BVTE

100 3000

FREC

=$F6

TEMFORRRV FROM RDORESS STORE

110 8000

TREC

=tF8

TENFORRRV TO RDDRESS STORE

120 S000

blk::

-=tl2

NUMBER OF BLOCKS TO MOVE (HEX)

130 8000

RSBM=*I300

RSSEMBLER/EDITOR ENTRV POINT

140 S000

150 S000

160 8000

R9S0

LDR

itFRHI

170 8002

85F7

5TR

FREG+ 1

180 S004

ft940

LDR

#rRLO

190 S006

85F6

SIR

FREG

200 S00S

FI902

LOR

#TOHI

210 seofl

85F9

STR

TREO+ 1

220 S00C

fl940

LOR

#T0LU

230 800E

S5F8

STR

TREG

240 S0I0

H2/2

LOK

«BLKS

250 S0I2

FI000

LOV

260 80 14

}

270 8014

;

280 SOI 4

BIF6 BLOCK LOR

iFREG).

290 8016

9IFS

STR

<:treg>.

300 SO IS

INV

310 8019

C052

CFV

#$52

CHECK FOR POSSIBLE END OF CODE

320 S0IB

F00B

BEQ

TEST

DO REST OF CHECK IF SO

330 S0IC>

C.0O0

CFV

IF NOT CHECK FOR END OF BLOCK

340 S0IF

D0F3

BNE

Block

350 8021

E6F7

INC

FREG+ 1

INCREMENT BLOCK POINTERS

360 8023

E6F9

INC

TREG+I

370 S025

DEX

DECREMENT BLOCK COUNTER

3S0 S026

O0EC

BNE

Block

390 8028

400 8028

£00/ TEST CPX

IF X=/ THEN UE'-RE FINISHED

410 802FI

O0E8

Bh-E

BLOCK

OTHERI'IISE

420 8020

;

430 S02C

4C00I3

JhP

RSBM

440 S02F

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No. 57 - February 1983

MICRO

moderate crashes can be made by call-
ing the move routine again and reset-
ting the 'next available storage location
pointer' to the end of the text file -i- 1.
This pointer is stored in location
$12FE,12FF and is set to $1391 upon in-
itialization. Cold entry to the
Assembler/ Editor is from $8000 and
the 'INIZ' prompt is displayed instan-
taneously. Warm entry is from $1300
and you should answer 'no' to 'INIZ',
as before.

Putting only these two utilities in
PROM is worth the cost and effort, but
there is more. PROM space from $9191
to $9800 is available for custom rou-
tines. I have my printer interface driver
here, a new keyboard service routine,
Autobasic, a smart terminal routine, an
EPROM programmer, and still have
space left over for future expansion.

There's another advantage! By mak-
ing BASIC-in-ROM BASIC-in-PROM,
you can fix the garbage collect bug that
exists in Microsoft BASIC Version 1,
Rev. 3.2. I have implemented the code
recommended by E. Morris in the June
'81 issue of PEEK(65) and am pleased
with the results. In fact, the word pro-
cessor I used to write this article is
written in BASIC and uses extensive
string manipulation.

The diagrams and schematics ac-
companying this article show you how
to make the necessary modifications.
Most of the cuts to the PC traces are on
the top of the board and are marked
with a.-ff—. Figures 3 and 4 show the
best places to make the cuts.

The jumpers (not shown in figure 3)
should be apparent in figure 2. 1 marked
the source of each added or changed
signal and abbreviated the schematic
for clarity. You should compare it with
the original before you attempt the

A12-
A13-

A15.
A14-

R/W-

Flgure 1: Chip Select Decoding

A10

A11-

D7
D6
D5
D4
D3
D2
D1
DO

2732

CE OE

$4000

74LS04

74LS02

A11-
A12-

A15-
A14-
A13-

15
-C|G

G
A
B
74LS139'

■ $5000
— $6000

$7000

TT/W

AO
A1
A2
A3
A4
A5
A6
A7
A8
A9
A10

WR _ _
OE CS

2016
OR

6116

D7
D6
D5
D4
D3
D2
D1
DO

$2000

-$2800

$3000

$3800

Figure 2

FROM U23-2 A14>
FROM U22-3 A15>

FROM U15-5 R/W)
FROM U23-1 A13).

MICRO

No. 57 - February 198;

Figure 3: Top View of PC Board

U27

Figure 4: Bottom View of PC Board

n n
n n D D

modification. Basically, all that is
necessary for the conversion is to
remove 02 from pin 21 and replace it
with All, wire in new output enables
to pin 20, and add the new chip selects
on pin 18.

The 2316's use high logic levels for
CS and therefore require the four sec-
tions of inverter U16. The 2732's use
low logic levels for CS or CE, so the in-
verters are not used.

You should have confidence in your
ability to make hardware modifications
before attempting these changes. The
entire project can be done in one eve-
ning and will provide you with in-
creased performance from your Super-
board U/CIP at moderate cost.

David Jones is a technical specialist for
Racal Milgo Inc., a Miami-based
manufacturer of data communications
products. He has a Superboaid II and has
redesigned the video circuitry for a true
32/64-chaiacter per line display, built a
parallel printer interface, adapted an
EPROM programmer via a 6522 VIA, and
customized the monitor program in
addition to the expansion outlined in this
article. You may contact Mr. Jones at 8902
S.W. 17 Terrace, Miami, FL 33165.

JMCftO

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No. 57 - February 1983

MICRO

Indirect Files Under OS-65D

by Richard L Tretheway

Several uses for the Indirect
files are discussed, Including
merging programs, a warm start,
and transferring programs from
one OSI operating system to
another.

Demo Programs

requires:

OSI with OS-65D V.3.3

The indirect file is one of the most
powerful and yet underused features of
Ohio Scientific's OS-65D operating
system. This file is a buffer in memory
that can be used for temporary storage
of either BASIC or assembly-language
programs.

You would use an indirect file, for
example, when you are in the midst of
writing a program and suddenly realize
that you either haven't created a disk
file for the program at all, or the created
file is no longer large enough to hold
the cvurent version. At that point, you
could either store the program in your
scratch file (that nobody seems to
remember to have ready for such pur-
poses), or you could use the indirect
file. To send your program to the in-
direct file just enter the command
"LIST < SHIFT > 'K' ". You will see
the program listed normally, but it is
also being stored in the indirect file buf-
fer. When BASIC returns the "OK"
prompt you enter a < SHIFT > 'M',
which marks the end of the file in
memory. Your program workspace is
now free to run the directory program,
or "CREATE" or "DELETE" as needed.
When you have created the proper file,
enter "NEW" to clear the workspace
and type a <CTRL> 'X'. Your pro-
gram will be reloaded into the
workspace intact. Don't be concerned
when you enter the < SHIFT > 'M' and

BASIC returns a syntax error. The
operating system knows what you
want done.

Those of you familiar with indirect
files probably noticed that I made no
mention of the POKEs to 9554 and
9368, which set the starting addresses
for input and output for the indirect
file. OS-65D was developed on and for
systems with 48K of memory and thus
these addresses are set by default to
$8000 hex. If you don't happen to have
48K, you will have to reset these ad-
dresses with the appropriate POKEs.
One good way to decide what number
to use is to figure out how many pages

of workspace memory you have, divide
it by two, and then subtact that num-
ber from the page number of the end of
your contiguous memory. For example,
on a 24K system running OS-65D V3.2
you have roughly 12K of free RAM,
which translates to 48 pages of
memory. Dividing that by 2 yields 24.
The top of 24K is page 96. 96 - 24 = 72
and thus, 72 is what I recommend you
POKE 9554 and 9368 with in your
BEXEC» so that it is always set up and
available when needed.

If you own an OSI disk system
manufactured before August of 1980,
you have probably cursed OSI's fast

Listing 1

10 REM- Program to add DATA statements to existing programs

20 REM- to set up L)SR(X) -functions.

30 S=INT( ( PEEK (8960) -59) /2) +59: POKE 1 33, S-1

40 SS=PEEK(B960) :REM- System Memory Size in Pages.

50 PRINT I (28) "To begin, I need to know the starting and ending"

60 PRINT"memory address where your machine code is in memory .": PRINT

70 PRINT"For the starting address, " s G0SUB490! SA=A

80 PRINT"For the ending address, ": G0SUB490:EA=A

90 PRINT! INPUT"Was this code assembled with an o-f-fset"!Y«

100 IFLEFT«(Y*, 1 ) <>"Y"THENPR INT; QF=0! GOTO 120

110 PRINT:PRINT"For the o-f f set , " ! GQSUB490! QF=A

120 NL=INT( (EA-SA) /15)+1:REM- # lines = size/15 + 1

130 SP=NL»52!REM- Space = ApproK . 52 bytes » Number o-f lines.

140 IF EA+SP < SS»256 THEN A= ( INT <EA/256) +1 ) «256! G0T0250

150 IF S»256+SP < SA THEN A=S*256 : G0T0250

160 IF (EA-SA)+SP < <SS»2S6) THEN200SREM- Will it ever -fit ?

170 PRINT! (2S) "This code needs to be reassembled higher in"

180 PRINT"memory in order for it to -fit in your available"

190 PRINT"RAM along with the generated indirect •file."!END

200 PRINT"This machine code routine is simply too large to -fit in"

210 PRINT"memory along with the generated indirect -file."

220 PRINT"You might try breaking it up into pieces and then"

230 PRINT"re-run this program on each individual piece merging"

240 PRINT"the results into a large program on disk."

250 PQKE9554, A/256: P0KE9368, A/256! REM- Set up indirect -file.

260 DA=A:SA=SA-OF!EA=EA-OF

270 PRINT"What line number should the DATA reading"

280 INPUT"start with "sLN: PRINT

290 INPUT"How much should I increment each line number ";I

300 POKEDA, 13:P0KEDA+1 , 10:DA=DA+2:REM- Initial <CR><LF>

310 0«=STR«(LN) ! G0SUB600: POKEDA, 32 : DA=DA+1

320 0«="FORX=" ! GGSUB600! Q«=STR«(SA) : GGSUB620: 0«="TO"

330 G0SUB600: 0*=STR«(EA) : G0SUB620! POKEDA, 58 : DA=DA+1

340 0*= "READY!POKEX,Y:NEXTX!RETURN" : G0SUB600

350 POKEDA, 13 : POKEDA+1,10 : DA=DA+2 : A=SA+OF

360 LN=LN+I ! 0«=STR«<LN) : GOSUB600: DC=0

370 0«=" DATA" ! G0SUB600

380 0«=STR«(PEEK(A) ) s G0SUB620

390 PRINT".";: IF P0S(0)=63 THEN PRINT! (12)

(Continued)

MICRO

No. 57 ■ February 1983

< BREAK > key more than once. One
of the foibles of OS-65D is that there is
just no good way for you to do a warm
start after the system has been reset by
a < BREAK >. But fortunately, OSI
didn't really desert you after all. The
indirect file can save all of your hard
work. Try booting your system and
enter BASIC with your "BEXEC»" pro-
gram still loaded in the workspace.
Now press the < BREAK > key. At the
"H/D/M" prompt, type "M" to enter
the machine code monitor, and then
press "G" for GO. You should now be
back in BASIC, albeit a crippled BASIC.
As previously described, enter "LIST
<SHIFT> 'K' ", followed by a
<SHIFT> 'M' at the "OK" prompt.
Now re-boot the system. Clear the
workspace with the "NEW" com-
mand. This time at the "OK" prompt
type a < CTRL > 'X' . Your program has
been re-loaded, intact, into the
workspace all ready to be run and/or
saved to disk. While I'm sure that this
is a patch that was added after BASIC
had been written for OSI systems, it
works and has saved me more hours
than I'd care to admit.

You can also use indirect files to
transfer programs from one operating
system to another. One of the ways
that OSI protects users from acciden-
tally trying to run incompatible soft-
ware from one operating system to
another is to use different disk formats
so that one DOS won't read files from
another. If you own a color video
system try booting up your "DEALER
DEMO" disk, press "P" for "PASS" to
enter BASIC. Now insert a regular OS-
65D disk in the drive and try to load the
"BEXEC»" from that disk. No soap,
right? Here again, indirect files can
help. All versions of OS-65D support
indirect files as does OS-65U. So, to
transfer programs from one OS to
another, load your program and send it
to the indirect file. Re-boot on the
destination disk. Type "NEW" to clear
the workspace and type a <CTRL>
'X', and you're all set to go.

Indirect files can merge programs.
Assembly-language programmers are
notorious for having little pet subrou-
tines that they use in many different
programs. If you are careful to use line
numbers that are dedicated to special
functions, you can use indirect files to
avoid having to retype those subrou-
tines every time you need them.

To illustrate a use for indirect files
while in the Assembler/Editor, try

Listing 1 (Continued)

400 IF A=EA+OF THEN 450: REM- Done ?

410 IF A>SS»256 THEN 160 : REM- Out o-f RAM ?

420 A=A+1 : DC=DC+1 ! REM- INC Address Si Data Counter

430 IF DC<15 THEN POKEDA, ASC ( " , " ) : DA=DA+1 : G0T0.380

440 POKED A, 13 : POKEDA+1,10 : DA=DA+2 : G0T0360

450 POKEDA, llsPOKEDA+l, 10: POKEDA+2, 93: POKEDA+3, 13:P0KEDA+4, 10

460 PRINTI (28) "The subroutine -for your USR(X) routine now resides"

470 PRINT"in the indirect -file. To add it to your program, load"

480 PRINT"your program into the workspace and type a <CTRL> ' X ' . " : NEW

490 PRINT"Enter the decimal address or hex address preceeded by a '*■"

500 INPUT" ";A» : PRINT : L=LEN(A*) : IF LEFT* ( A*, 1 ) ="*"THEN530

510 F0RX=1T0LEN(A*) : C»=MID» (A», X , 1) : IFC*< "0"ORC»>"9"THEN490

520 NEXTX;A=INT(VAL(A») ) sRETURN

530 A=0: IFLEN(A*)<2THEN490

540 FORX=2T0LEN<A») : C*=MID» < A», X , 1) : IFC»< "0"THEN490

550 IFC»<="9"THENA=A+VAL(C»)«(16'(L-X) ) ! 60T0580

560 IFC»<"A"0RC*.>"F"THEN490

570 A=A+(ASC(C»)-55)«(16'-(L-X))

580 NEXTX

590 RETURN

600 F0RX=1T0LEN(0») ; POKEDA, ABC (MID* (0», X , 1) )

610 DA=DA+l! NEXT: RETURN

620 0*=R I GHT* ( 0* , LEN ( 0* ) - 1 ) : 60T0600

loading an assembly-language program.
Now type "P < SHIFT > 'K' ". As with
BASIC, you will see your program
listed on the screen. Type a < SHIFT >
'M' to close the file. Now type "I" and
respond with a "Y" to the prompt
"INIZ?". Confirm that the workspace
is clear by typing "P" again. Now try
our usual < CTRL > 'X' . Your program
will be reloaded. The operating system
stores your program in discreet ASCII
when you use the indirect file. When
you download a program from the in-
direct file, the OS interprets the incom-
ing lines just as if you had typed them
in from the keyboard. Should you have
a program in the workspace while you
are downloading a program, duplicate
line numbers will be replaced by the new
lines just as if you had typed in a correc-
tion to a line with a syntax error in it.

But a crafty assembly programmer
could arrange a library of disk files con-
taining his most used subroutines, be-
ing careful to avoid duplicate line
numbers. Whenever one of those pro-
gams is needed, he would just send the
destination program that was resident
in the workspace to the indirect file,
then load the subroutine file and merge
the two by typing a <CTRL> 'X'. It's
not perfect, but at least it can save a lot
of typing.

To illustrate another use of indirect
files, I have written a short program.
This program takes a machine-code
program (resident in memory) and con-
verts it into a subroutine written in
BASIC that does the appropriate POKEs
to set up a USR(X) function. It could be
used to transfer a machine-code pro-
gram from your disk system to a

friend's system that just has a cassette.
He still won't be able to read your disk,
but at least he would have a copy of
your program in a form he can use.

To use the program, save it on disk
and then assemble your machine-code
program in memory. Since the memory
maps of disk and cassette systems are
very different, my program takes any
offsets that you had to use into account
when creating the new subroutine.
When the machine code is in place, re-
enter BASIC and run my program. It
will ask you where the machine code is
in memory [and will accept the hex ad-
dress if you didn't figure it ahead of
time), what line numbers to use for the
subroutine to be created, and finally,
offsets, if any. After the program has
run just type a <CTRL> 'X', since my
program has already NEWed itself out
of existence. You can now save this
program on disk, or run it and it will
faithfully recreate your machine-code
program. Note that my program was
written using OS-65D V3.3 and has
some print statements that do cursor
addressing under that OS. Those of you
still running 65D V3.2 can eliminate
the parts of the print statements that do
this (i.e., "!(12|" inline 280 should be
eliminated) .

You may contact the author at 5405
Cumberland Rd., Minneapolis, MN 55410.

iiMCRO

No. 57 ■ February 1983

MICRO

LjjN

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SOFTWARE FOR CBM 64 E

Word Processino

Qcommodore

INTERFACES

ADA-1 450 Serial S149

ADA-1600 Parallel 149

RS232 caDle for Vic or 64, 2m 30

Video/Audio cable for 64 & monitor _ 25

MONrrORS — Great resolution
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Panasonic, 13" Color S375

Amdek Color I 330

NEC JB 1201M, 12" Color 330

NEC JB 1201. 12" green phospfior 170

Amdek Video 300L, green phospfior 175

BUSINESS SOFTWARE

Spellmaster Dictionary (great for WordPro') S199

OZZ Data Base System (8050) 240

Silicon Office (database, wp) 995 (

Wordcraft 80 289

VisiCalc (new expanded) 199

Dow Jones Portfolio Management System (RS232) 120

WordPro 4+ or 5 ^ . 299

Tfie (l/lanager 199

Legal Time Accounting 425

I.R.M./L_ ' 295

BPI A,'R, G/L, Job Cost, Inventory, Payroll 325|;

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Computer Tutoring Game (COCO) 50

General Ledger 199

Pet Emulator (emulates 4.0 basic) 30

CBM EasyCalc (for the 64) 99

CBM EasyFinance 50

CBM EasyPlot 80

CBM EasyScan (appointment manager) 80

Sprite-Magic (build sprites on screen with

Joystick, save to disk or cassette) 30

Assembler Package for CBM 64 (cassette)
Editor (creates and updates source code),

Assembler, Loader, Disassembler 50

Mail Mate 50

IEEE Interface (64) 100

Parallel Interface 90

RS232 Interface (modems, printers) 45

VIC PRODUCTS

VIC 20 Computer, 5K $199

Vic Datasette Recorder 60

Vic 1541 Disk Drive 395

VIC MODEM (for CBM 64) 100

VIC 1525 Graphic Printer (for CBM 64) 325

8K Memory Expansion Cartridge 49

16K RAM 99

24KRAM 155

IEEE Interface (VIC) 85

Gorf (great arcade game) 30

Omega Race 30

Midnight Drive 23

VIC 3 slot Expander 43

VIC 6 slot Expander 83

Seawolf 23

Cosmic Cruncher 23

Arcade Joysticks — Heavy duty with 2 firing
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SuperPET (5 languages, 2 processors)

CBM 8032 Computer 80 column

CBM Memory Expansion, 64K

PET 4032, 40 Column

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CBM D9060, 5 Mg Hard Disk

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PRINTERS — DOT MATRIX

CBM 4022,8Qcps;graphics

CBM 8023,150 cps.graphics

Okidata 82A,120cps,'serial or par

Nee 8023A(parallel)

MICRO

No. 57 - February 1£

/AlCftO

From Here To Atari

By Paul S. Swanson

Languages

The language C, offered in interpreter
and compiler versions, was recently
added to the list of languages available
to Atari 400 and 800 systems. FORTH,
PILOT, and several other high-level
languages have been available for some
time. But despite the large number of
choices for languages, the most popular
seem to be BASIC and assemblers.

There are several versions of BASIC
and several assemblers. Of the
assemblers, the original cartridge ver-
sion from Atari can be implemented on
even a 16K system, which is an
advantage for those who have not ex-
panded their systems to 48K. Atari also
provides a macro assembler. I chose the
Synassembler (Synapse Software),
which assembles faster than the Atari
cartridge and is less expensive.

Almost every Atari computer is pur-
chased with a version of BASIC —
usually the cartridge BASIC. There is
also a form of Microsoft BASIC for
those of you who want to, on your
Atari, run software that was written for
other computers. Because of the note
and point style of random access used
on the Atari, there is a big difference in
the disk commands between the Atari
version and the versions on the Apple,
Radio Shack, and IBM computers.

Monarch Data Systems (P.O. Box
207, Cochituate, MA 01778) offers a
BASIC compiler. Compiled programs
can run 4 to 12 times faster than the
interpretive code. Several restrictions
limit the use of this compiler, but these
are easily circumvented for most ap-
plications. For example, the compiler
uses fixed point arithmetic instead of
the slower floating point, so there are
no trigonometric functions. There is
also no RND( function supported, so
you must use a PEEK[53770) and ex-
tract a random number by multiplying
that result (a random number between
and 255), then dividing to get a
number in the proper range. The LOAD

and RUN statements are also not sup-
ported, so the program caimot chain to
other programs. For more information
on this compiler, contact Jeff Goldberg
at Monarch Data Systems.

Hardware

Many letters from readers express
an interest in the hardware and ask
questions about the keyboard I was
marketing. I recalled the keyboard
because several manufacturers produce
keyboards just like it, and they can pro-
duce them more cheaply than I can.
However, I am vmting an article
describing how I built my keyboard
(you can build one for under $20 plus a
weekend of time instead of buying one
for over $100).

Several questions have been asked
about the controller jacks at the front of
the Atari console. These jacks provide
the simplest interfaces to any external
device. They are connected to eight
A/D (analog to digital] converters and a
PIA (peripheral interface adapter). See
the last page of your Atari hardware
manual for a diagram of the pins and
jacks. Port A controls the joystick pins
of jacks 1 and 2 and Port B controls
those on jacks 3 and 4. As you look at
the computer from the front, the MSB
is on your right and the LSB is on your
left. To use them for input, you do not
need special codes — just PEEK(54016J
for Port A or PEEK(54017] for Port B.

To set up pins for output, you must
write to the direction control register.
An example of setting up Port B as an
8-pin output follows: (to use Port A in-
stead, subtract one from the PEEK and
POKE addresses)

100 POKE 54019,56
110 POKE 54017,255
120 POKE 54019,60

POKEing 54019 with a 56 tells the
computer to take the next POKE to
54017 as a direction control code. This
is a binary code with each bit corre-
sponding to a pin on the jacks. If the
corresponding bit is 1, the pin is de-
fined as output and if it is a zero, the
pin is set up as input.

Once you have completed that sec-
tion of code, you may then POKE to
54017 whatever you want to send out.
If you POKE there and then PEEK the
same location, you will get back the
code you sent, as if it were a RAM loca-
tion. Therefore, if you set the low-order
four bits as output and the upper four as
input, you can send a code out then
read the input combined with the code
you sent. This makes scanning con-
trollers simple to set up in the soft-
ware. The value you read is what you
sent plus 16 times the value that your
device sends back.

The plugs for those jacks are not
easy to obtain. You can get plugs that
work from APX, but they cost almost
$7 each (plus postage) and you must
have a minimum order. Just check
around in your area for a suitable store.
My source is Eli Computers in Cam-
bridge, MA.

A ground and +5 volts are
available, also. For larger projects it is
best to have an independent power sup-
ply for your device. According to Atari,
you can draw as much as 300 mA from
these pins (total — not per port), which
should be enough to drive many
smaller devices.

Thanks to Devin MacAndrew for
calling my attention to an error in my
November column. The 64K board I
mentioned, according to the advertise-
ment he sent me, is available from
Mosaic ( Mosaic Electronic Inc., P.O.
Box 748, Oregon City, OR, 97045]
and bank selects only above the 48K
boundary, using a 4K address space not
used by the hardware registers or
operating system.

Future Columns

As many columns as possible will
be based on mail I receive, so by all
means, keep writing. Please mention
specific applications and include a
description of your hardware configura-
tion. The next few columns will deal
with various aspects of the hardware
available on standard Atari computers.

JMCftO

No. 57 - February 1983

MICRO

In The Beginning
Was The
Word. . .

,vHK

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Q^'

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V\J'

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^To**

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MICRO

No. 57 - Februar

It's All Relative - Using CBM's
Relative Records, Part 3

byJimStrasma

This third instailment describes
the use of a key file as an index
into a relative file. The author
draws examples from the update
module of a powerful mail-list
package (available from the
author and various user groups).

Last month we learned how to create
relative files, using the "Create"
module of Chris Bennett's "Mail List
4040." This time we will set up a key
file as a framework for accessing
relative files. Our example is the "Up-
date" module of Chiis Bennett's mail
list. As before, you may want it handy
as you read.

Cautions

Bennett's "Update" module, loaded
from "4040 menu," is the largest
module in the package. Be careful
about changing it. If you lengthen it
more than a couple of lines, you will
need to increase the value POKEd into
location 43 (or your BASIC'S equiva-
lent) in line 1060 of the "Setup"
module, as explained in part one of this
series (55:37). If you want to save space
for more names, shorten this module
and change the above line to match.

As supplied, there is only enough
main memory free to maintain about
1200 names, even in disk drives far
larger than the 4040. This is also about
the size limit for a relative file on the
8050 disk drive; [i.e., six-side sectors
referencing 120 sectors, containing 254
bytes of data each). The 8050 file size
limitation does not apply to other
Commodore disk drives.

Using a Key File

A relative file permits simple access
to any record within a file, as long as
we know its position within the file
relative to other records. However, that
is rarely the case. We are more likely to
know the name we want than the

record number. To deal with this, most
file-handling programs use one or more
additional files as indexes to the main
file. These files usually contain a value
for each record in the main file. The
values are ordered in some way, usually
reflecting the alphabetic ordering of
some field within the records of the
main file. Fields used this way are called
key fields, because they act as keys to
gain access to the file. In Bennett's
mail list, the key field is a combination
of two fields — the first ten characters
of the last name, followed by two char-
acters of the first name.

In smaller programs, the key file
may actually contain the contents of
the key field, along with the number of
its record in the main file. This method
provides the fastest access, but uses
memory quickly. Therefore, large pro-
grams usually store the key value on
the disk, accessing it there when needed.
Either way, the key file is kept sorted at
all times by the contents of the key
field. This allows records to be located
with a binary search (see Alfred Bruey's
article on page 37 for more on binary
searches), a technique offering very
quick access to information already
sorted. Here is the binary search used
in the mail list:

4460 FS =

4580 I = 1

4590 J = NV

4600 IF I > J THEN 4700

4610 K = INT((l-l-J-l-1)/2)

4620 l%=K%(K)

4630 GOSUB 5320:REM READ KEY

4640 IF K$ = KY$ THEN 4680

4650 IF K$ < KY$ THEN J = K - 1 :

GOTO 4600
4660 K =: K -I- 1
4670 GOTO 4600
4680 RR = K%(K)
4690 FS = 1
4700 RETURN

Variable FS starts equal to zero and
is changed to -i- 1 if key value K$ exists
in the key field. Notice that array K%( |
contains only the numbers of records in
the main file. Subroutine 5320 returns
the key field from the main file in
variable KY$:

5310 REM READ THE KEY IN RELATIVE

RECORD NUMBER 1%
5320RECORD#1,(I%)
5330 IF DS THEN 1690
5340INPUT#1,KY$
5350 IF DSTHEN 1690
5360 RETURN

If you don't have BASIC 4, you will
need to substitute for the RECORD#
statement above (as described in part
two of this series (56:52).

By making the key field the first one
in each record, it can be read with a
single INPUT# statement. Note that
the only difference in BASIC 4 between
reading a field from a relative file and
reading it from a sequential one is the
RECORD# statement preceding the read.

Keeping Keys Sorted

Next, let's consider the way keys
are kept sorted. At any moment there is
no more than one key value out of order
— the one currently being added. When
a record is to be added to the file, its
key field is first checked, using the
binary search above, to see if it is a
duplicate of one already in the file. This
is not allowed in the mail list, though
some programs do permit duplicate
keys. Next, another subroutine makes
room for the new key in the K% ( ) array
that will become the updated index file
at the end of the program run:

2360 REM DO BINARY INSERT

ON KEY K$
2370 IFP <1 THEN P=1
2380 IF NV = 1 THEN K%(1)=1:G0T0

2490:REM EXIT

No. 57 - February 1983

MICRO

2390 EZ = P + 2:IF EZ > NV - 1 THEN

EZ = NV-1
2400 FOR K = P TO EZ
2410 : l% = K%(K)
2420 : GOSUB 5320:REM READ KEY
2430 ; IF K$ < KY$ THEN P = K:K = EZ
2440 NEXT
2450 IF K$ > = KY$ THEN K%(NV) =

RR:GOTO 2490:REM EXIT
2460 E = NV

2470 SYS DL,0,P,E,K%(0),ZZ
2480 K%(P) = RR
2490 RETURN

Lines 2370-2390 and 2450 handle the
top and bottom limiting values. The
other lines perform a binary insert to
find quickly the place where the new
key field should go in the file. Once
located, the SYS call in line 2470 opens
a space for it in the K%( J array. Until
we cover these calls at the end of this
series, readers without BASIC 4 may
use a BASIC substitute:

2470 FOR GO = E TO P + 1 STEP - 1
2473: K%(QQ)=K%(QQ-1)
2476 NEXT

Where QQ is simply an otherwise
unused variable. Once a hole is opened,
it is filled with the value of the current
record number RR.

When a record is deleted, the pro-
cess is similar. First, its key and record
number are found using the binary
search above. Then, after double-
checking that the user really wants to
delete that record, its place in the key
array is removed, with each value
above it moving down one:

3250 IF P<> NVTHEN SYS

DL,1,P,E,K%(0),ZZ
3260 K%(NV) =

Or, in BASIC:

3250 IF P = NVTHEN 3260
3252 FOR 00 = P TO E - 1
3254 : K%(00) = K%(00+ 1)
3256 NEXT
3260 K%(NV) =

This process frees a space in the
relative file for re-use. To handle this,
Bennett's mail list remembers the de-
leted record number, RR, in a separate
array DE%| ], indexed by ND, the
number of currently deleted records.

3270 ND = ND-H1
3280 DE%(ND) = RR

When new records are added later,
these spots are re-used first, as we will
see next time. As supplied, Bennett's
mail list dimensions DE%( ) to NR, the
maximum number of records. If you
were suddenly to delete every one of
the list's 1000 name capacity, the array
would hold it. On the other hand, if you
want to have over a thousand records,
you may need to reduce the capacity of
this array. Unless your list is highly
volatile, a dimensioned size of NR/10
should be adequate. Array sizes are de-
fined in line 2070 of the set-up module.

Reading the Key File

To be useful, key file information
has to be in memory during the pro-
gram run and on diskette, preserved for
future use. Further, when its informa-
tion is changed, the disk copy needs to
be replaced. Naturally, we want to do
all this as quickly, compactly, and
safely as possible.

The first aid to speed is that the key
file is read only once per session; if the
currently needed key is already in
memory from earlier use of this or
another module, it is not read again.
Variable GD (got data) keeps track of
this for us:

1160 IFGD< >1 THEN GOSUB

4720:GD = 1: REM READ IN KEY
FILE IF HAVEN'T

Since we will always want to read the
entire key file at once, and in order, it is
kept in a sequential disk file. When it is
to be read, this routine does the work:

4710 REM READ IN KEY FILE
4720 D0PEN#9,D(DD),"INDEX" ON

U(UN)
4730 IF DSTHEN 1690
4740 INPUT#9,F$,NR,NV,ND
4750 IF DSTHEN 1690
4760 IF NV = OTHEN 4790
4770 FOR I = 1 TO NV:INPUT

#9,K%(I):IF DS = OTHEN NEXT:

GOTO 4790
4780 GOTO 1690
4790 IF ND=0THEN 4820
4800 FOR I = 1 TO ND:INPUT#9,

DE%(l):IFDS = 0THEN

NEXT:GOTO 4820
4810 GOTO 1690
4820 DOLOSE 9

In BASIC 2, substitute:

4720 OPEN#9,UN,9,DD$ + "INDEX,
SEOUENTIAL.READ"

4725 GOSUB 60010:REM CHECK DISK

STATUS

(also use as line 4745, and within

lines 4770 and 4800, just before

IF DS.)
4820 CLOSE 9

Line 4720 opens the sequential file
"index" to read. Then a few special
values are read in:
F$, the name of the mail list
NR, the next record number to be used
NV, the maximum number of records

it may contain
ND, the number of deleted records to

be replaced before adding new ones
After this, the key array K%( ] is filled
in a single line, as is the DE%( ) array
two lines later. The reason for cram-
ming these into single lines is to save
time in reading it. FOR... NEXT loops
contained entirely on a single line work
far more quickly than those spanning
several lines, especially this far along in
the module. The difference is due to
not having to scan for line numbers
within the loop. As written, the pro-
gram falls through lines 4770 and 4800
only if there is a DOS error. If it does
fall through, the session will be
terminated.

Writing the Key File

At the end of each use of the "up-
date" module, Bennett's mail list
checks to see if the key file needs to
be rewritten to disk. If nothing has
happened to change the file in mem-
ory, variable UP will equal zero. Any
other value triggers a rewrite of the
key file. This flag variable is checked in
line 1390:

1390 IF UP THEN GOSUB 5060:
REM WRITE KEY FILE

Due to a shortage of space on the
4040 diskette, "update" does not use
the best method of replacing the "in-
dex" file. Ideally, we would first
rename the existing file as "old", then
save the updated file under the correct
name, and finish by scratching "old"
after the new copy is properly closed.
Unfortunately, this requires enough
spare storage on the diskette to hold
two copies of the "index" file, and we
don't have that much room to spare
when the file is full. The same problem
keeps us from using the "@" SAVE-
WITH-REPLACEMENT option of CBM
DOS. It works much the same way,
making a spare copy of the new version

MICRO

No. 57 - February 1983

before destroying the old one. If you
have a larger capacity disk drive, either
of the above methods would work well.
But on the 4040, we do it this way:
5050 REM WRITE OUT KEY FILE
5060 PRINTTAB(11)"WRITING KEY

FILE"
5070 SCRATCH "INDEX", D(DD) ON

U(UN)
5080 IF DS> 1 THEN 1690

In BASIC 2, substitute:

5065 OPEN 15,UN,15

5070 PRI NT#1 5, "SCRATCH " + DD$ +

"INDEX"
5075 GOSUB 60020:REM CHECK DISK

STATUS WITHOUT REOPENING

FILE 15
(Considering how often BASIC 2 users
will be opening and closing file 15, it
would probably be better to open it
once in the setup module, and not close
it again until the program ends.)

After eliminating the old copy of the
file, "update" now proceeds to save a
new version:

5110 D0PEN#9,D(DD),"INDEX",

W ON U(UN)
5120 IF DS THEN 1690
5130 PRINT#9,F$C$NR;C$NV;C$ND
5140 IF NV = 0THEN 5170
5150 FOR I = 1 TO NV:PRINT#9,

MID$(STR$(K%(I),2):NEXT
5170 IFND = OTHEN 5190
5180 FOR I = 1 TO ND:PRINT#9,

DE%(I):NEXT
5190 IF DSTHEN 1690
5200 DCLOSE 9
5210 IF DSTHEN 1690

In BASIC 2, substitute:

5110 OPEN 9,UN,9,DD$ + "INDEX,

SEQUENTIAL,WRITE"
5130 PRINT#9,F$C$NR;C$NV;

C$ND;C$;
5150 FOR I = 1 TO NV:PRINT#9,

MID$(STR$(K%(I),2)C$;:NEXT
5180 FOR I = 1 TO ND:PRINT#9,

DE%(I)C$;:NEXT
5200 CLOSE 9

Notice the use of C$ (containing the
carriage return character) as a delimiter
in line 5130. This is the only safe way
to write multiple variables in a single
PRINT* statement. Due to a bug in
BASIC 2, it is also the only way to
fmish a PRINT* statement to the disk,
as shown in the alternate lines above.
Note too that semicolon spacing be-
tween variables is the default, and only
needs to be made explicit when vari-
able names could be confused.

The complex expression in line
5150, MID$(STR$(K%[I),2), saves disk
storage space at the cost of file rewrite
speed. When a numeric variable is
PRINT#ed to the disk, a leading space
is left for its sign, if any. Since a file
can't have a negative record number,
the space is wasted — and would fill
four disk sectors in Bennett's mail list.
The expression strips off the sign space
by turning the number into a string and
ignoring its first character. If your disk
has more capacity, improve your re-
write speed by using a simple PRINT #
"nstead, as in line 5180. (Since the
number of deleted records is usually
small, little would be gained by using a
complex expression in line 5180.)

Also note that once the file is suc-
cessfully opened, the disk status is not
checked again until an attempt has

been made to write all the data in the
file. This saves time, and if there is an
error anywhere in the process, the final
check will catch it. DOS errors during
PRINT # are not fatal to the program if
ignored. However, don't try this when
reading the file. Failing to check disk
status after every INPUT* will likely
halt the program on any DOS error.

What About Alternate Keys?

Careful study of Bennett's mail list
will reveal an alternate key, in addition
to the primary one, handled in much
the same way. We left it out of our dis-
cussion because it is not fully
developed. At present, it merely re-
cords record numbers — a chore easily
handled without a second key. In an in-
complete 8050 version of the mail list,
Bennett went further, using the code
field as the alternate key field.

If you need one or more alternate
keys, just maintain them along with the
primary one, changing all of them when-
ever any one is altered. Essentially, ex-
tra keys are a trade-off. Maintaining
them increases the time needed to add,
delete, and change records, and adds to
the complexity of the program. But
maintaining these keys eliminates the
delay of sorting before printing records
out in ZIP code or other new orders.

Next month we finally get this
beast on the road, reading and writing
relative file data.

The author may be contacted at 1280
Richland Av., Lincoln, IL 62656.

JMCftO

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No. 57 - February 1983

fvllCRO

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A Binary Search Routine

by Alfred J. Bruey

This article describes the binary
search technique and then
presents two demonstration
programs. One sets up a sorted
test file that can be searched
using a binary search; the other
sets up a sorted test file and
allows a record to be inserted in
Its proper place. This binary
search technique can be used
as the basis for a complete data
base system.

Sort Routines

require:

Any Microsoft BASIC
computer

Your computer is handy for keeping
lists of names, right? But how do you
find a particular name, especially if
your list is in random order? You could
write a program to start at the begin-
ning of the file and compare items one
by one with the name you want. Of
course, this process would be extremely
time-consuming. And if the name you
were searching for wasn't there, you
wouldn't know until you had searched
the entire list!

Unfortunately, there is no better
method to search for an item if the list
is in random order. Therefore, you
should make sure youi file is in alpha-
betical order; the rest of this discussion
will assume your file is in order.

The binary search routine presented
here can be used to find items on a
sorted list. You can also use this
routine to find where you should place
a new item.

The principle of the binary search is
as follows (note that in any of the steps
below, you are done if you get an exact
match) .

1. Check the first item on the list. If
the value you're searching for is less

than this, the item isn't on the list.

. Go to the middle value on the list. If
the value there is greater than your
search value, you've got the search
narrowed to the first half of the list.
If not, you've got it narrowed to the
last half of the list.

, Next try the middle value of the in-
terval found in step 2 above. Now
you have the search narrowed down
to one quarter of the list.
The next comparison will narrow
the search to l/8th of the hst, the
next to l/16th, etc. Therefore,
counting your compare with the first
item on the list, you will have your
missing value narrowed down to
l/16th of the list after only five
compares, l/32nd of the list after six
compares, l/64th after seven com-
pares, etc.

5. Continue this process until you find
the item, or reduce the list to one
item.

Subroutine Description

The binary search subroutine
shown as part of figure 1 (lines 10000
and greater) performs as follows:

1. The value you are searching for is
put in NM$.

2. The file being searched is assumed to
be in array N$ .

3. If the value NM$ is found in array
N$, its location is returned as the
value of variable J. (The first item in
array N$ isN$(Oj.)

4. If NM$ isn't found in array N$, the
value of J will be the index of the
next array value larger than NM$.

Let's look at some examples with a
file N$ that contains the following

Listing 1: Routine to Find Records

10 REM ***********••*••••*•••••••

20 REM ROUTINE TO FIND RECORDS*
30 REM •••••••••**••••••••••••*••

35 DIM NS(IOOO) :N-10

4 DATA BILL, CARL, CARL, DON, JOHN , MAR I E, MARY , PETE, ROGER, ROGER, ZZZZZ

50 FOR 1=0 TO N

60 READ N$(I)

7 NEXT I

80 INPUT "ENTER VALUE YOU WANT TO SEARCH FOR (ENTER XXX TO STOP)";NMS

90 IF NMS»"XXX" THEN STOP

100 GOSUB 10000

110 PRINT "INDEX ";J:" FOUND FOR SEARCH ARGUMENT ";NMS

120 GOTO 8

10000 REM *************************

10010 REM BINARY SEARCH SUBROUTINE*

10020 REM *************************

10030 J»0

10040 IF J»=l THEN 10200

10050 IF N<»0 THEN 10200

10060 IF NMS<NS(0) THEN 10200

10070 J1 = 0:J2=-N

10080 J=-INT( (Jl+J2)/2)

10090 IF NM$-N$(J) THEN 10140

10100 IF NM$<N$(J) THEN J2»J:G0T0 10120

10110 Jl-J

10120 IF JOINTC (Jl+J2)/2) THEN 10080

10130 J»J+1:G0T0 10200

10140 IFJ-0 THEN 10200

10150 IF J"l AND NM$=-N$(J-1) THEN J-0 : GOTOIO 20

10160 IF J-1 THEN 10200

10170 FOR J»J TO 1 STEP -1

10180 IF NM$<>N$(J) THEN J-J+1:G0T0 10200

10190 NEXT J

10200 RETURN

No. 57 - February 1983

MICRO

names (we will be using this file later
in the sample computer program) :

ex No.

Name

BILL

CARL

DON

JOHN

MARIE

MARY

PETE

ROGER

ZZZZZ

Note the following:

1. The same name can appear more
than once on the list. The value of J
returned will be the index of the first
appearance of the name.

2. The last value in the file must be
larger than the last value that could
appear. The value 77777. will usually
satisfy this requirement.

The program in figure 1 sets up the
sample file shown earlier. With this
routine, we can enter search values and
receive index values from the subroutine.

Enter and run this program for the
following search values as shown in the
NM$ column. The response should be
the index value given in the J column.

NM$

JOHN

ADAM

BILL

YOST

MARIE

NANCY

PETE

Note that ADAM and BILL both
return a value of 0, and NANCY and
PETE both return a value of 7. You will
have to put a line in your program to
check whether you have actually found
the value of NM$, or whether you have
found the value that would have fol-
lowed NM$ if it had been on the file.
The next two lines of coding can be
added to what you've previously
entered. These lines allow you to see if
the value was found or not. Enter them
and run the program again to check the
results.

112 IF N$(J) = NM$THEN PRINT
■■RECORD FOUND":PRINT:PRINT

114 IF N$(J) < > NM$THEN PRINT
"RECORD NOT FOUND":PRINT:PRINT

Listing 2: Routine to Insert Records

10 REM *••••••♦♦♦♦««««*«««.*.«.«»

2 REM ROUTINE TO INSERT RECORDS*
30 REM *•••••♦•♦••««••♦«•••»««««*

35 DIM N$(1000) :N-10

40 DATA BILL,CARL,CARL,DON, JOHN, MARIE, MARY, PETE, ROGER, ROGER, ZZZZZ

50 FOR I-O TO N

60 READ N$ (I)

70 NEXT I

80 INPUT "ENTER VALUE YOU WANT TO INSERT (ENTER XXX TO STOP)»;NM$

90 IF NM$-"XXX" THEN 250

100 GOSUB 10000

120 REM *****••••••••**««••♦«***♦*

130 REM ROUTINE TO INSERT RECORD *
140 REM •**•••***•♦♦•••••••*«***.*

150 PRINT"INSERTING RECORD IN FILE"

160 FOR I=N TO J STEP -1

170 N$(I+1)-N$(I)

18 NEXT I

190 N-N+1

200 N$(J)-NM$

210 PRINT "RECORD INSERTION COMPLETE"

220 PRINT "*****♦••*••*•***•**•*****.

2 30 PRINT: PRINT

2 40 GOTOBO

250 REM PRINT NEW FILE

2 60 FOR 1-0 TO N

270 PRINT N$(I)

2 80 NEXT I

2 90 STOP

10000 REM ***•••••••♦••••*•••••*•..

100X0 REM BINARY SEARCH SUBROUTINE*

10020 REM *************************

1003 J-0

10040 IF J="l THEN 10 200

10050 IF N<»0 THEN 10200

10060 IF NM$<N$(0) THEN 10200

10070 J1-0:J2-N

10080 J-INT( (Jl+J2)/2)

10090 IF NM$-N$(J) THEN 10140

10100 IF NM$<N$(J) THEN J2=J:G0T0 10120

10110 J1"J

10120 IF J<>INT((Jl+J2)/2) THEN 10080

10130 J-J+1:G0T0 10200

10140 IFJ-0 THEN 10200

10150 IF J-1 AND NM$.N$(J-1) THEN J-0 : GOTOIO 200

10160 IF J-1 THEN 10200

10170 FOR J-J TO 1 STEP -1

10180 IF NMS<>NS(J) THEN J-J+1:G0T0 10200

10190 NEXT J

10200 RETURN

Now let's see how to insert new
records into a sorted list. Figure 2
shows the coding that, along with the
search subroutine, will perform this
function. This program will ask you to
enter values. As you enter them, they
will be placed in their proper (alpha-
betical) place in the file. When you
enter 'XXX' as a record, the program
will stop and print out your new list.
You will lose all your new values when
the program ends, but this isn't serious
since this is only a test program. In
practice, you would read all the data in
from a tape or disk and then write them
back to a tape or disk when all the
changes have been made.

For an exercise, write a delete rou-
tine. You should be able to model it
after the insert routine in figure 2.
Notice that you don't always have to
check for the full record. You can, for
example, replace N$(I) with LEFT$
(N$(I),3) in the subroutine if you only

want to check the first three characters
for a match.

As you might have guessed, the
binary search routine can be set up as
the foundation for a complete file
maintenance system. If you are able to
find a record, it's usually a simple mat-
ter to change it or delete it. The major
disadvantage is that you must be able
to hold your entire file in RAM (Ran-
dom Access Memory] for the length of
the run. This restricts the size of the
file you can use. As an extension, you
might want to write a routine to read
in, say, 100 records and search through
them, then read in another 100 records
and search through them, etc. This
method would be slower, but it would
allow you to search disk or tape files of
any length.

Contact Mr. Bmey at 201 S. Grinnell St.,
Jackson, MI 49203.

iiMCftO

MICRO

No. 57 - February 1983

AARDVARK
TRS-80 COLOR OSI VIC-64 VIC-20 SINCLAIR TIMEX

TUBE FRENZY

(by Dave Edson)
This is an almost indescribably fast action
arcade game. It has fast action, an all new
concept in play, simple rules, and 63 levels
of difficulty. All machine code, requires
Joysticks. Another great game by Dave
Edson. TRS 80 COLOR ONLY. 16k and
Joysticks required. $19.95.

QUEST - A NEW IDEA IN ADVENTURE
GAMES! Different from all the others.
Quest is played on a computer generated
map of Alesia. Your job is to gather men
and supplies by combat, bargaining, explor-
ation of ruins and temples and outright
banditry. When your force is strong enough,
you attack the Citadel of Moorlock in a
life or death battle to the finish. Playable
in 2 to 5 hours, this one is different every
time. 16k TRS-80, TRS-80 Color, and Sin-
clair. 13K VIC-20. $14.95 each.

AOVENTURESM!

These Adventures are written in BASIC, are
full featured, fast action, full plotted ad-
ventures that take 30-50 hours to play. (Ad-
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reading a book except that you are the main
character as you give the computer com-
mands like "Look in the Coffin" and
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No. 57 - February 1983

MICRO

BASIC Renumber for OSI

by Paul Krieger

A BASIC language routine to
renumber BASIC programs in
memory and save to tape.

Renumber

requires:

OSI C1P

This BASIC language routine is written
for an OSI CI P. It will probably run on
other OSI machines and, I suspect,
could be adapted to most Microsoft
BASIC machines as well. To do this
you would have to: 1. change X = 769
throughout the program to the ap-
propriate starting address for your
machine, 2. revise the instruction table
lines 40320-40490 for your particular
BASIC, and 3. change the syntax of the
BASIC to your format.

To operate this program, first key it
into your machine after a cold start and
then test it to make sure there are no
keyboard errors or omitted lines. You
can test it by typing RUN40280. The
first message on the screen will be
"ENTER RANGE OF OLD #'s YOU
WISH TO UPDATE(LOW,HIGH)".
Enter the lower number, comma,
higher number. For the test enter
40280,41500, which is the range of this
routine. The program will then ask you
for the new number (BEGIN,STEP).
Enter the new beginning number and
the increment you want between num-
bers. An appropriate answer for this
would be 1, 1, which will cause the first
line to be 1 instead of 40280, and each
line thereafter will be 1 greater. There
will be a pause after your reply while
the program builds the branch table.

Once the preliminary work is done,
the progam will type the message
"START TAPE RECORDER IN
RECORD/PLAY MODE NOW". This

indicates it is ready to make the up-
dated copy of the program. Start your
recorder using a blank tape and type
space, return. You will see the program
listing with the new numbers. After the
tape is made, you will have the un-
changed program in memory and a copy
of it with new line numbers on tape. To
run the new version press BREAK and
cold start your machine. Then LOAD
the tape as you would any other

program. To renumber any other
BASIC program, first load it into
memory then load this renumber
routine in with it by mounting the
cassette and typing load again.

This program relies on the cassette
tape as a working medium. There are
two reasons why I chose to write the
program this way. First, by making a
tape instead of changing line numbers
in memory, it is easy to handle line

Listing 1: Renumber BASIC

40280 REM ROUTINE TO RENUMBER BASIC BY Paul Krieger

40290 REM Nov. 8, 1981

40300 REM BT-BRANCH TABLE, LN-LINE NUMBER OF DESTINATION

40 310 DIMIT$(67);DIMBT(200) :DIMLN(200)

40 320 IT$(0)-"END":IT$(1)-"FOR":IT$(2)-"NEXT":IT$(3)-"DATA"

40330 IT$(4)-"INPUT"!lT$(5)-"DIM":IT$(6)-"READ":IT$(7)-"I.ET"

40 3 40 IT$(8)-"GOTO":IT$(9)-"RUN":IT$(10)-"IF";IT$(11)-"RESTORE"

40 350 IT$(12)-"GOSUB":IT$(13)-"RETURN":IT$(14)-"REM":IT$(15)-"STOP"

40 360 IT$(16)-"ON":IT$(17)-"NULL":ITS(18)-"WAIT"!lT$(19)-"LOAD"

40 370 IT$(20)-"SAVE"lIT$(21)-"DEF":ITS(22)-"POKE":IT$(23)-"PRINT"

40380 IT$(24)-"C0NT":IT$(25)-"LIST"!IT$(26)-"CLEAR":IT$(27)-"NEW"

40 390 IT$(28)-"TAB"!lT$(29)-"T0":IT$(30)-"FN":IT$(31)-"SPC("

40400 IT$(32)-"THEN":IT$(33)-"NOT":IT$(34)-"STEP":IT$(35)-"+"

40410 IT$(36)-"-":IT$(37)-"*";IT$(38)-"/":IT$(39)-"A"

40420 IT$(40)-"AMD"!lT$(41)-"0R":IT$(42)-">":IT$(43)-"-"

404 30 IT$(44)-"<";IT$(45)-"SGN":IT$(46)-"INT":IT$(47)-"ABS"

40440 IT$(48)-"USR"lIT$(49)-"FRE":IT$(50)-"POS":IT$(51)-"SQR"

40450 IT$(52)-"RMD":IT$(5 3)-"LOG":IT$(54)-"EXP":IT$(55)-"'COS"

40460 IT$(56)-"SIM":IT$(5 7)-"TAN":IT$(58)-"ATN":IT$(59)-"PEEK"

40470 IT$(60)-"LEM"!lT$(61)-"STR$":IT$(62)-"VAL":IT$(6 3)-"ASC"

40480 IT$(6 4)-"CHR$":IT$(65)-"LEFT$":IT$(66)-"RIGHT$"

40490 IT$(67)-"MID$"

40500 REM INITIALIZE

40510 PRINT "ENTER RANGE OF OLD t'S YOU WISH TO UPDATE"

40520 INPUT"(L0W,HIGH)";LR,HR

40530 INPUT"ENTER new NUMBER: (BEGIN, STEP)" :BG , ST

40540 X-769JREM BEGIN OLD DESTINATION PASS "ODP"

40550 Q-OtREM SET TABLE INDEX TO BEGINNING

40560 NA-PEEK(X+1) :REM GET NEXT INSTRUCTION HIGH BYTE

40570 NA-NA*256:REM SETUP HIGH

40580 NB-PEEK(X):NA-NA-t-NB:REM ADD IN LOW

40590 REM NA IS NEXT ADDRESS, NB IS WORK

40600 IFNA>0THEN40980:REM EXIT OLD DEST PASS

40610 L-PEEK(X+3) ;L-L*256:NB-PEEK(X+2) :L-L+NB

40620 IPL>HRT8EN40980

40630 W-X+4JREM TO TEXT OF INST

40640 FORI-0TO72:REM SCAN FOR BR

40650 C-PEEK(W+I) ;REM BRANCH TABLE ARGUMENT

40660 REM 144-ON, 44-COMMA AFTER "ON"

40670 REM 1 36-GOTO, UO-GOSUB, 160-THEN, n7-RUN

40680 IPC-I44THENS-l!REM "ON" SET SWITCH TO 1

40690 IFS-1THEN40720

40700 IFC-I36ORC-I40ORC-I60ORC-137THENGOSUB40 7 7O

MICRO

No. 57 - February 1983

Listing 1: Renumber BASIC (continued)

40710 GOTO40730

40 720 IFC-136ORC-U0ORC-160ORC-13 70RC-44THENGOSUB407 70

40730 IFC-OTHENI-72!S-0:REM RESET "ON-GOTO" SWITCH

40740 NEXTI

407S0 X-NA!GOTO40S60:REM CONTINUE U NEXT LINE

40760 REM ENTER HERE FOR BRANCHING ONLY

40770 REM I NOW POINTS AT POSSIBLE "THEN"

40780 IFCO160THEN40800

40790 B-PEEK(I+W+1) :IFB>57THENRETURN:REM "THEN" W EXPR-IGNORE

40800 B-C

40810 FORK-0TO6;REM FIND LEFTMOST * OF DESTINATION

40820 C-PEEK(K+I+W)

40830 IFC>47ANDC<58THENK-K+6

40840 NEXTK

40850 KR-K-6:REM FIND RIGHT SIDE

40860 FORK-KRTOKR+6 :C-PEEK(K+I+W)

40870 IFC<480RC>57THENK-K+6

40880 NEXTK

40890 K-K-8

40900 J-10

40910 BT(Q)-PEEK(K+I+W) : BT(Q)-BT(Q) -48

40920 K-K-1

40930 C-PEEK(K+1+W)

40940 IFC<48ORC>57THEN40970

4095 C-C-48!C-C*J:J-J*10:BT(Q)-BT(Q)+C

40960 GOT040920

40970 C-B:Q-Q+l!RETURN

40980 REM LINK TO DESTINATION

40990 X-769

41000 BD-BG

41010 NA-PEEK(X+1) !NA-NA*256:NB-PEEK(X) :NA-NA+NB

41020 IFNA-0THEN41130

41030 L-PEEK(X+3) ! L-L*256 ;NB-PEEK(X+2 ) :L-L+NB

41040 IFL>HRTHEN41130

41050 FORq-OT0200iREM LINK OLD TO NEW

41060 Y-X+3:LN-PEEK(Y):LN-LN*256:REM HIGH OF LINE #

41070 Y-X+2;L0-PEEK(Y) !LN-LN+LO;PRINTLNj !REM PRINT LINE #

41080 NEXTQ

41090 IFL<LRORL>HRTHEN41110

41100 BD-BD+ST

41110 X-NA:G0T041010

41120 REM RENUMBER

41130 SAVE!PRINT"START TAPE RECORDER IN RECORD/PLAY MODE NOW"

41140 INPUT"PRESS SPACE/RETURN WHEN PAST LEADER"jB$

41150 Q-0

41160 X-769

41170 NA-PEEK(X+1) :HA-SA*256 :NB-PEEK(X) !tJA-tJA+UB

41180 IFNA-0TUEN41S00

41190 Y-X+3:LN-PEEK(Y) ;LN-LN*256iREM HIGH OF LINE #

41200 Y-X+2:L0-PEEK(Y) : LN-LN+LOi IFLN>HRTHEN4 1500

41210 IFLN<LRORLN>HRTHEN41240

41220 PRINTBG; :BG-BG-t-ST

41230 G0T0412S0

41240 PRINTLNj!REM PRINT LINE*

41250 W-X-t-4

41260 FORI-0TO72

41270 C"PEEK(W+I)

41280 IFC-OTHENX-NA: 1-7 3: G0T04 1430

41290 IFC-44THENPRINTCHR$(C) ; :COT041340

41300 IFC<1280RC>195THEN41420

41310 C-C-128!PRINTIT$(C) i

41320 IFLN<LRORLN>HRTHEN41430

41330 C-C+128:IFC-160THENB-PEEK(W+I+1) ;IFB>57THEN4 1430

41340 IFC-144THENS-l!REM SET "ON-COTO" SWITCH

41350 IFS-1TUEN41380

41360 IFC-136ORC-14OORC-160ORC-137TUEN4140O

41370 G0T041430

41380 IFC-1360RC-1400RC-160ORC-1370RC-44THEN41400

41390 GOTO41430

41400 GOSUB41460

41410 I-I-)-B-ltGOT041430:REM BYPASS NEW DEST #

41420 PRINTCHR$(C) ;

41430 NEXTI

41440 S-0!PRINT

41450 GOT041170

41460 B$-STR$(LN(Q)) :B-LEN(B$) :PRINTRICHT$(B$ , B-1) ;

41470 B-LEN(STR$(BT(Q))) :REM PRINTING NEW LINE #

41480 q-Q+1

41490 RETURN

41500 rORDL- 1T04000 !NEXTDL:P0KE5 17 ,0 : END

numbers that can vary from one digit to
as many as five. Second, by making a
tape, the program can renumber itself,
which it could not do if it were changing
memory. A byproduct is that a copy of
the original program is still in memory
in case there are bugs in this renumber-
ing routine.

BASIC is kept in memory in a com-
pressed format. The first two bytes are
the address of the next instruction in
memory. This is a binary value with a
range of from 771 to 65383. The next
two bytes are the current BASIC line
number, which is also in binary. The
range of this field is to 63999. Then
comes the text of the BASIC instruc-
tion. Any BASIC command, statement,
operator, or function is reduced to a
single character in the range 128 ($80)
to 195 ($C3).

A line number destination [branch),
as in a GOTO, is kept in the graphic
format. To renumber in memory it is
necessary to deal with the branch line
numbers by expanding or compressing
each line in memory from the end of
the subject line to the end of the BASIC
instructions.

The fourth line of the program in-
cludes two dimension statements using
200. This represents the maximum
number of branches in a program. So far
this has worked fine for me, but you
may wish to make this value larger or
smaller according to the size of your
programs or memory or both.

If you load this routine into mem-
ory and all the line numbers are larger
than those already in memory, there
probably won't be a timing problem. If
the line numbers of this routine are
smaller than those already in memory,
there may be a timing problem as the
machine will relocate all the instruc-
tions in memory once for each line read
in. If this is the case, you will see par-
tial lines being read from the tape and a
lot of error messages on the screen. You
can overcome this problem by placing
some nulls in the renumber program
prior to creating the master tape.

The author may be contacted at 3268 S.
Cathay Cr., Aurora, CO 80013-

JMCRO

No. 57 - February 1 983

MICRO

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No. 57 - February 1983

LANGUAGES

SuperPET APL

by Terry Petersen

This article gives a brief
description of several APL
textboolcs currently available, an
overview of APL in general, and
the SuperPET's microAPL in
particular.

Before I owned a Commodore Super-
PET, I had heard of a programming
language called APL but never had ac-
cess to a machine that could run it.
Therefore, my curiosity about this un-
tried language influenced my decision
to buy a SuperPET. I think it is fair to
say microAPL is the most unorthodox
of the languages supplied with the
SuperPET. Programmers raised on
FORTRAN and BASIC refer to it as
"the closest to hieroglyphics I've ever
seen," and "a write-only language."
MicroAPL is also the largest of the four
interpreters by Waterloo Computer
Systems, Ltd. (WCS) that came with
my SuperPET (it nearly fills the 64K
bank-switched expansion RAM). Con-
versely, it has the smallest user manual
— 108 pages versus 137 for microPascal
and 221 for microBASIC. I soon con-
cluded I needed more help getting
started in APL than was available in the
Waterloo documentation. To learn
more about the language I pestered my
local librarian to obtain several APL
textbooks via interlibrary loan.

Books on APL

APL inventor Kenneth Iverson
wrote the first book about the lan-
guage. Published in 1962, it is entitled
A Piogiamining Language.^ It describes
some of the rationale of APL and how
to implement it. I recommend Mr. Iver-
son' s book only to those interested in
APL's guts — it is not a good tutorial
for learning to write APL programs.

Books in Print currently lists about
a dozen APL textbooks. I borrowed five

of them, selected more or less at ran-
dom, all of which are better than the
original for learning APL programming.
I found the most folksy approach to
teaching APL in Howard A. Peelle's
APL: An Introduction.'^ Written in an
unusual style, this book is organized
into nine tutorial sessions. The pages
are printed to look like an APL terminal
printout with hand- written notes added.
The lessons seem easy to follow and
there are frequent questions for the
reader to test his understanding of the
material. I think this book is a good in-
troduction to APL for those with little
or no computer experience. Others will
probably find it a bit plodding.

APL: An Interactive Approach by
Leonard Gilman and Allen J. Rose^ also
assumes no particular computer or
mathematics background. The book is
geared to IBM equipment, as are all the
others I've seen, but it is fairly com-
plete in describing the language ele-
ments, and is quite usable with the
SuperPET as long as you ignore the in-
formation about workspace storage,
etc. (Note: In APL you save and load
workspaces rather than programs.)
This book seems to be more widely
available than Peelle's; I foimd it in a
imiversity bookstore.

Of the five textbooks I selected, my
favorite is Handbook of APL Piogiam-
ming by Clark Wiedmarm.* This book
is more terse than Iverson' s or Rose's,
but is more explanatory than WCS's
manual. The copy I borrowed from the
library was clothbound, but the copy-
right information page indicates it is
available in paperback also.

APL Piogramming and Computer
Techniques by Harry Katzan, Jr.^ is
notable for its inclusion of several real
APL programs for study. The edition I
saw, however, was published in 1970
and appears rather dated; for example,
there is no mention of the domino

function. Perhaps later editions are
more up-to-date.

Finally, I looked at A Course in APL
with Applications by Louis D. Grey.*
This book seems to me to have been
hastily prepared, with many (typo-
graphical?) errors as well as what ap-
pear to be outright program errors.
Such confusion does not contribute
positively to the learning experience
and is most unwelcome in a textbook.

Accessible Programming

When Keimeth Iverson invented
APL, FORTRAN was practically the
only high-level language available for
scientific programming. At that time
FORTRAN dialects were very restric-
tive and demanded that the program-
mer be a fairly sophisticated com-
puterist. Even if you could get your pro-
gram to compile successfully, there
was a good chance some esoteric fea-
ture of the compiler's method of inter-
nal number representation would give
imexpected results.

The main intent of Iverson' s new
language was to make programming
more accessible by freeing program-
mers (still presumed to be mathe-
matically oriented) from mundane con-
siderations, such as whether or not a
number is stored in the computer in in-
teger or floating-point form, or whether
or not a particular variable is a scalar or
an array of dimension x. APL achieves
this intent; the same APL variable may
contain (at different times during pro-
gram execution] integer, floating-point,
or even character data, and it may
become a scalar or an array merely by
assigning such data to it. A very power-
ful side-effect of this lack of 'type' is
that an APL 'function' may return with
no difference in coding scalar, vector,
or array results, depending only on
given argument(s)!

Compared to other languages of the

No. 57 - February 1983

MICRO

LANGUAGES

early sixties, APL is certainly a paragon
of versatility. Even today, I think it is
unmatched in its freedom from variable
types. This freedom comes at a price, of
course. Since there are no declarations
of variable types (as in Pascal) nor im-
plicit types [as in FORTRAN and
BASIC), you are forced to discover from
its context what kind(s) of data a
variable contains. This process of
discovery can be puzzling and time-
consuming when you read an APL pro-
gram written by someone else — or
yourself, six months earlier.

Also, since APL tends to substitute
array operations for things that would
be written as loops in other languages,
its coding is unusually compact. I
doubt that even the most experienced
APL programmers skim through un-
familiar APL code the way you might
with Pascal or well- written BASIC.
However, APL's compactness does
have its virtue: microAPL is the Super-
PET's fastest interpreter, hands-down.
There simply isn' t as much source code
to scan in performing a given task as in
other languages. For example, consider
as a benchmark the filling of an array
with the sequence 1, 2, 3, ..., 1000.
This task takes (as coded below) 11
seconds in microBASIC, 5.25 seconds
in CBM BASIC, and only 1.18 seconds
in microAPL.

APL Implementations

APL implementations, including
microAPL, contain many more built-in
functions than are found in most other
languages, even on mainframe com-
puters. There are functions for finding
the maximum or minimum value in an
array, sorting arrays, and 'cutting' and
'pasting' arrays to make smaller or
larger arrays. There is even a function,
called the 'domino,' for finding the
'least-squares' fit of data to a model
equation! [Domino will also, trivially,
invert a matrix.)

Aside from being rather difficult to
read, APL's worst deficiency, in my
estimation, is its primitive branching
mechanism. Its only branch instruc-
tion is a close relative of BASIC'S 'ON
X GOTO 1,...,N.' There is no IF...
THEN... ELSE, WHILE..., UNTIL...,
etc. — in short, no stmctuied program-
ming. This is not as bad as it sounds
because APL's rich complement of
built-in functions and extensive use of
arrays obviate many loops and branches.
However, since it lacks the sorts of
program-flow control statements found

in most other, more modem, lan-
guages, efficient APL coding requires a
different programming style and mind-
set. For example, the array-filling
benchmark mentioned above is coded
in BASIC as follows:

100 DIM A(1000)
110 FOR I = 1 TO 1000
120 A(l) = I
130 NEXT I

In APL it is written as:
A *- 1000 e I 1000

where the meaning of the above one-
liner is ' 'Assign to A the 1000-element
vector formed from the integers 1 to
1000." It's not too hard to see why the
APL interpreter makes such short work
of this benchmark. It scans one short
line of source while the poor BASIC in-
terpreter is stuck with scanning lines
120 and 130 a thousand times!

As an example of how not to write
APL, you could code this benchmark
more closely to the BASIC version
this way:

A *- 1000 eO
I *- 1
XX: A[l] «- I
I «- I -I- 1
-(I < 1001)/ XX

where the meaning of these APL lines
may be guessed by comparison with the
BASIC version. This awful mess takes
121 seconds to run and is a glaring ex-
ample of what might be called 'pidgin
APL.' I hope my remark about mindset
is now clear.

I should hasten to add, for the
benefit of any fervent structured-
programming enthusiasts, that it is
possible to impose some of the
cosmetics of structured programming
on APL in order to make it more
readable. If you have a SuperPET, see
the excellent work done by an
anonymous WCS programmer in the
sample workspace "MASTERIVUND"
on the SuperPET tutorial diskette. This
sort of veneer, however, doesn't really

make up for the lack of control
statements in APL.

A feature APL does share with
modem structured languages is the
high degree of modularity. APL pro-
grams usually are written as a collec-
tion of functions, similar to Pascal pro-
cedures and functions, which may use
either local or global variables. Each
function may have zero, one, or two
arguments, and may or may not retum
an explicit result. The limitation to
two arguments is not as restrictive as
you might imagine because each argu-
ment can be an array. However, any
assumption within the function about
the rank of its arguments reduces its
generality. For example, consider the
following APL function:

[0] Z *- EQUALS 3 A
[1]Z*-A = 3

If A is a scalar, the function EQUALS 3
returns a scalar value of 1 if A is 3 and
returns otherwise. In addition, if A is
any numeric array whatever, this func-
tion will retum an anay of I's and O's
of the same shape as A. On the other
hand, the following function will ac-
cept only one type of argument — a
numeric vector (and it ignores all but
the first three elements) :

[0] VOLUME *- PARALLELAPIPED X
[1] VOLUME *- X[1] X X[2] X X[3]

As you might suspect, this is another
example of pidgin APL. A more proper
APL version of PARALLELAPIPED
would be:

[1] VOLUME «-x/X

This second version uses the 'reduc-
tion' (/) operator to signify multiple ap-
plication of the X's operator. In this
version a vector argument would result
in the scalar product of all the elements
of the vector; and an array argument
would yield an array of one lower rank
(one less subscript) with each element

MICRO

No. 57 - February 1983

LANGUAGES

equal to the product of the elements of
the argtiment array obtained by fixing all
but the last subscript! (Mindset again.]
APL's extensive use of arrays tends
to require large amounts of memory.
On the SuperPET this is particularly
troublesome because the microAPL in-
terpreter stores all numeric quantities
in floating-point form, requiring five
bytes each. Furthermore, microAPL
doesn't allow all the available RAM to
be used for variable storage. I haven't
worked out just how the division be-
tween program and variable space is
decided, but it works out such that an
otherwise empty workspace cannot
contain even one 3000-element
numeric array. However, it can contain
four 1000-element arrays! In most
cases, it seems you probably will run
out of variable space before the user
RAM is actually full. The RAM-
gobbling situation could be reduced
dramatically if some form of byte- or
integer- (double-byte) numeric storage
could be used where appropriate.

APL Character Set

APL has a strange character set. The
wealth of built-in functions of APL are
invoked via a vast array of unusual
characters. I find this a problem even
though I'm familiar with the Greek
alphabet; those who are not face even
greater difficulty. The situation in APL
could be compared to requiring BASIC
programmers to read and write their
programs in the 'tokens' used internally

by the interpreter instead of English
keywords. It's a pity Mr. Iverson didn't
invent the keyword-token translator
along with the rest of APL.

Besides requiring memorization,
the characters of APL present a prac-
tical problem when printing and typing
them. There are special APL print-
wheels available for daisy-wheel
printers, and some dot-matrix printers
may be programmed to 'draw' APL
characters; but the APL keyboard is
still troublesome. There are so many
APL characters they won't fit all at
once on a regular keyboard, so some of
them are formed by ' overs triking' to
make one character out of two simpler
characters. This is awkward and re-
quires you to remember which two
characters to use. Mercifully the two
characters may be typed in either order.
[Ed. note: Terry had to limit his pro-
gram examples to ones containing the
Greek and math characters our typeset-
ter has.)

In summary, there are things I like
very much about APL. Its free-form
variables permit very elegant and clever
coding of mathematical problems. (I've
written a one-line function that com-
putes the next generation of a LIFE
game, but I can fill only about half the
screen because of the SuperPET' s RAM
limitation.) There are also things I
dislike about APL. Its odd character set
and lack of flow-control statements are
anachronisms. MicroAPL, specifically,
seems to be a pretty faithful implemen-

tation of the IBM language, as adver-
tised. It could benefit significantly,
however, from some micro-oriented ex-
tensions, such as integer- or byte-
numeric arrays (perhaps resulting from
Boolean operators) . Being a polyglot at
heart, I have enjoyed learning such an
unusual language as APL.

Bibliography

1. Iverson, KennethE., A Piogiamming
Language, John Wiley & Sons, Inc.,
New York, 1962.

2. Peelle, Howard A., APL: An Intio-
ducdon, Hayden Book Company,
Inc., Rochelle Park, New Jersey,
1978.

3. Gilman, Leonard and Rose, Allen [.,
APL: An Intemctive Appioacb, John
Wiley & Sons, Inc., New York,
1976.

4. Wiedmann, Clark, Handbook of APL
Piogiamming, Petrocelli Books,
New York, 1974.

5. Katzan, Jr., Hairy, APL Piogiam-
ming and Computei Techniques,
Van Nostrand Reinhold Company,
New York, 1970.

6. Grey, Louis D., A Couise in APL
with Applications, Addison-Wesley
Publishing Company, Inc., Philip-
pines, 1976.

You may contact Mr, Peterson at 8628
Edgehill Ct., El Cerrito, CA 94530.

JMCftO

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No, 57 - February 1983

MICRO

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MICRO

No. 57 - February 1983

LANGUAGES

EDIT: An ATARI FORTH
Screen-Oriented Editor

by Mike Dougherty

EDIT uses the Atari 800 display
as a text window into a FORTH
disk screen, and allows full use
of the Atari special function
keys to prepare FORTH
applications.

EDIT

requires:

Atari 800 with 24K
Atari 810 disk drive
APX fig-FORTH

The Atari Program Exchange version of
FORTH, "APX fig-FORTH," comes
with the sources for two line-oriented
editors on disk. Although line editing is
greatly enhanced by using the Atari
screen edit keys, a general video screen
editor makes software development
easier. EDIT implements a video screen
editor for the Atari 800. This 2.6K-byte
application can be modified to run on
most memory-mapped video FORTH
systems. With modification of the low-
level terminal words, EDIT should be
adaptable to FORTH systems contain-
ing a serial terminal with an ad-
dressable cursor.

EDIT Design

The two objectives of EDIT are to
provide a useful video screen editor and
to maintain full compatibility with
APX fig-FORTH. Specifically, the
following points are considered:

1. Retaining FORTH's 16-line by
64-character text screen.

2. Making FORTH LISTs or TRAIDs of
edited screens visually acceptable.

3. Allowing screens to be compiled by a
FORTH LOAD.

4. Making the video reflect the current
state of the text.

5. Causing the video screen editor to
execute with the Atari's default
38-character line length.

Listing 1: EDIT for Atari APX fig-FORTH

SCR

# 60

bv Mike Dougherty

2 ( APX -fig-Forth Screen Editor

3 (

4 (

5 (

( This editor allows the user

'. to edit a Forth screen using

( the Atari display as a te::t

( window into the Forth screen

( To load EDIT: 60 LOAD

< To EDIT screen #n: n EDIT

SCR

10
11

12
13
14
15

SCR

# 61

< CONSTANTS / VARIABLES FDR EDITOR

VARIABLE
VARIABLE
3 VARIABLE
3 VARIABLE

IB CONSTANT
2 CONSTANT

22 CONSTANT
VARIABLE

17 VARIABLE

CLINE

CCHAR

LINEOFF

CHARDFF

TOP-BOT

REDGE

LEDGE

SIDE

EXTRAOFF

( Current line number, iZl-15

( Current char number, 0-&3

( 0-f+set -for 1ST text line

( 0-f + set for le-ft margin

< Top ■?? bottom window char

( Right edge window char

( L.e-ft edge window char

( Current side of screen

( Extra line screen position

VARIABLE STOP

VARIABLE BAV-BUF 64 ALLOT

# 62

! READ SCREEN SCR INTO MEMORY )

( Editor exit flag

( Buffer for deleted line

(

)

16 DO

I SCR .3 (LINE)
DROP UPDATE DROP

LOOP

CLINE
CCHAR
SIDE

( Initiali:
( ...

4
5
6

9
10

12
13
14
15

SCR # 63

( PR I MAT I VE SCREEN MANIPULATIONS )
1

2 : ECLEAR ( )

3 XGR ( Clear

( For each line of the screen )
( Read .!< get the ADDR, LENGTH )
( Mark the block of memory )
( next screen line )

to 1ST LINE )
to 1ST CHAR )
to LEFT SIDE )

1 752

: POINT-CURSOR

85 !

84 C\ ;

: CURS0R3

CLINE a LINEOFF S +

CCHAR 3

SIDE 3 IF 32 - ENDIF

CHAROFF S + ;

— ■>

/ideo via GRAPHICS )
( Inhibit ATARI system cursor )

( row col )

( Save col in system shadow )
( Save row too — only 1 byte )

( — ■- row col )

( Compute vi deo posi t i on )

( Base value -for col )

( Adjust if RIGHT side )

( Add le-ft margin )

No. 57 - February 1983

MICRO

LANGUAGES

6. Performing logically equivalent
functions on the screen text with all
special edit keys of the Atari 800.
To use the Atari display, and main-
tain compatibility, EDIT uses a text
window of 16 lines by 32 characters. A
FORTH screen is thus divided in half —
the left side (SIDE = Oj and the right
side (SIDE= 1]. The ciirrent side of the
FORTH screen is displayed on the
video screen with a solid line around
the text area. The current text position
is indicated by inverse video, as in the
normal Atari display. In addition to the
text window, the other half of the cur-
rent line is displayed at the bottom of
the video screen.

In my applications, the left side of a
FORTH screen is used for actual
FORTH code and the right side is
reserved for comments. Thus, when
viewing a FORTH screen, all the code
on the left side (SIDE = 0) may be ex-
amined at once, while only one com-
ment line is displayed at a time as the
cursor is moved from line to line. So
far, 32 characters have been enough to
code a logical FORTH step, and 32
characters are usually adequate to com-
ment that step. In addition, this inter-
pretation of a FORTH screen en-
courages a vertical style of FORTH
definitions, with a comment for each
step. Considering the low cost of
diskettes, I prefer to spend a small
amount of money for the comments of
a vertical definition, rather than to
spend a large amount of time decipher-
ing terse, horizontal definitions, con-
taining few step-by-step comments.

A final pragmatic reason for select-
ing the 32-character text window lies in
the fig-FORTH treatment of disk
blocks when read into memory. Con-
secutive fig-FORTH disk blocks are not
necessarily stored in memory con-
secutively. Further, a disk block in
memory must also contain disk-related
information. Fortunately, after a disk
block is read into memory, the starting
address of any 64-character line may be
retrieved by the FORTH word (LINE).
Since the characters of each line are
stored consecutively in memory, a
32-character text window is easily
manipulated. A text window not fitting
evenly into 64 characters would have to
be handled by overlapping from block
to block.

Implementation

EDIT is implemented as a tvun-key
application. That is, once EDIT is in-

Llstlng 1 (continued)

SCR » 64

< PRIMITIVE SCREEN MANIPULATIONS)

2 :

CURSOR

CURSORS

POINT-CURSOR ;

SCREEN-CURSOR

CURS0R3

SWAP 40 « +

106 C3 256 «

960 -

+ DUP

C3 128 XOR

SWAP CI :

15 -

-y

SCR »

(
1

2 :

PRIMITIVES FOR DISPLAY >

HLINE

34 DO

TOP-BOT EMIT

LOOP ;

7 :

LADDR

CLINE a SCR 3 (LINE) DROP

SIDE 3 IF 32 + ENDIF ;

11 :

EADDR

CLINE 3 SCR 3 (LINE) DROP

SIDE 3 0= IF 32 + ENDIF ;

15 -

— /■

SCR «

<
1

PRIMITIVES FOR DISPLAY )

ELINE

LEDQE EMIT

LADDR 32 TYPE

REDQE EMIT ;

7 1

XLINE

LEDGE EMIT

EADDR 32 TYPE

REDGE EMIT ;

15 -

SCR 4t

<
1
2 :

PRIMITIVES FOR DISPLAY )

WRITE-LINE

CLINE 3 LINEOFF 3 +

CHAROFF 3 1 -

POINT -CURSOR

ELINE ;

S :

WRITE-EXTRA

EXTRADFF 3 LINEOFF 3 +

CHAROFF 3 1 -

POINT-CURSOR

12
13
14

XLINE ;

15 -

SCR *t

(

PRIMITIVES FOR DISPLAY >

TOP

LINEOFF 3 1 -

CHAROFF 3 1 -

POINT -CURSOR

HLINE ;

B :

BOT

LINEOFF 3 16 +

CHAROFF 3 1 -

POINT -CURSOR

12
13
14

HLINE ;

15 -

( Get video row and col pos )
( Point ATARI text cursor )

( Get video row and col pos )

< Form GR.i3 mem addr o-f-f set )

( Get top o-f memory addr )

( Backup to 1st o-f di spl ay )

( Farm mem addr of cursor )

( Bet screen display, invert )

( Put inverse video back )

( )

( For horizontal wi ndow span >
( Put a bar i n each char )

( addr )

< Compute mem addr a-f 1 ine )
( Adjust -for le-ft side )

( addr >

< Compute mem addr o-f 1 i ne )
( Ad just -for ri ght side )

( >

( Output le-ft window edge )

< Type actual text line )

( Output r i ght wi ndow edge )

( >

( Output le-ft wi ndow edge )

< Output text line over -flow )
( output right window edge )

( )

( Get vi deo line number )

( Poi nt to le-ft border pos )

( Point ATARI text cursor )

< Output edit line here )

( )

< Get video line number )

( Point to le-ft border pos )

( Point ATARI te:-:t cursor )

( Output extra line here )

( )

( Be-fore 1st line video )

( posi tion o-f le-ft wi ndow )

( Point ATAf^I text window )

< Output a horizontal line )

( >

( A-f ter 1 ast 1 i ne vi deo )

< Posi tion o-f le-ft wi ndow )
( Point ATARI text window )

( Output a horizontal line )

MICRO

No. 57 - February 1983

Listing 1 (continued)

SCR * 69

a < PRIMITIVES FOR DISPLAY >
1

2 : ETITLE

3 lil CHAROFF 3 POINT-CURSOR

4 . " Screen: " SCR ?

5 1 CHAROFF 3 POINT-CURSOR

6 . " Side: " SIDE ? ;
7

9
llil
11
12
13
11
15

( )

< Point to 1st video line )
( Type the screen number )

( Point to 2nd video line )

< Type the screen number )

SCR tt 70

( DISPLAY CURRENT SCREEN ,)
1

2 : DISPLAY

3 ECLEAR ETITLE

4 TOP

5 CLINE 3

6 16 DO ,

7 I CLINE I WRITE-LINE

8 LOOP

9 CLINE '

10 SIDE 3 IF 32 ELSE ENDIF

1 1 CCHAR '

12 EOT

13 WRITE-EXTRA

14 CURSOR SCREEN-CURSOR ;

15 — >

(

)

( Clear video, put title >

( Output top o+ window )

( Save current line on stack

( For each line in text )

(

Set CLINE and output it )
NeKt Forth text line )
Restore current line )
( Get start depending on side
( Store as current col pos )
( Output bottom o+ window )
( Output current line ovr+low
< Position cursor, show it )

SCR #71

( CASE STATEMENT BY DR. C. E. EAKER, FORTH DIMENSIONS CV2,*t3] )

2 : DOCASE ?COMP CSP 3 ' CSP 4 : IMMEDIATE

7
8
9
10
11
12
13
14
15

CASE 4 7PAIRS COMPILE OVER COMPILE = COMPILE (3BRANCH
HERE , COMPILE DROP 5 ; IMMEDIATE

ENDCASE 5 7PAIRS COMPILE BRANCH HERE ,
SWAP 2 [COMPILE] ENDIF 4 ; IMMEDIATE

ENDCASES 4 7PAIRS COMPILE DROP
BEGIN SP3 CSP 3 = 0= WHILE
2 CCOMPILEl ENDIF REPEAT
CSP I ; IMMEDIATE

SCR # 72

( CURSOR MOVEMENT PRIMITIVES )
1

2 : MOVE-RIGHT < )

Z CCHAR .3 1+ < Get/increment char pos )

4 SIDE 3 IF C Handle wrap around on side )

5 DUP 64 = IF DROP 32 ENDIF ( Over 63 goes to 32 on right )
ELSE

DUP 32 = IF DROP ENDIF ( Over 31 goes to on left )

ENDIF
CCHAR

9
10
U : RIGHT

12 MOVE-RIGHT SCREEN-CURSOR

13 : RIGHT-CURSOR

14 SCREEN-CURSOR RIGHT ;

15 — >

SCR # 73

( CURSOR MOVEMENT PRIMITIVES )

< Store new current char )

( ,

( Move and set cursor )

( )

< Restore cursor, move )

10
11
12
13
14
15

MOVE-LEFT ( )

CCHAR 3 1 - ( Get/decrement current pos )

SIDE 3 IF ( Wrap around on side )

DUP 31 = IF DROP 63 ENDIF ( Go to 63 on right wrap )
ELSE

DUP -1 = IF DROP 31 ENDIF ( So to 31 on le-ft wrap )
ENDIF

CCHAR ! ; ( Store new char pos >

LEFT

MOVE-LEFT SCREEN-CURSOR :
LEFT-CURSOR

SCREEN-CURSOR LEFT :

< )

( Move and set new cursor >

( )

( Restore cursor, move >

LANGUAGES

voked, it interprets all user keystrokes
until the end of the edit session. In
general, the words called by EDIT
should not be executed from the key-
board. Since the EDIT words manipu-
late the screen, results of direct execu-
tion can be confusing. EDIT is invoked
by pushing the screen number on the
data stack and calling EDIT. For exam-
ple, to edit screen number 60, type:

60 EDIT

Listing 1 is the EDIT application occu-
pying screens 60 through 86 on my
EDIT source disk. The original EDIT
text was entered with the APX fig-
FORTH editor (27 LOAD] and rewrit-
ten with the debugged version of EDIT.
The basic structure of EDIT is
straightforward. As defined on screens
85 and 86, EDIT reads a screen into
memory, displays the left half
(SIDE = 0) on the video display, and
sets a stop flag to zero (no stop). The
main loop is executed until the stop
flag is set to a non-zero value by one of
the FORTH words EXIT, EABORT,
ENEXT, or ELAST. EDIT inputs a ter-
minal key each pass through the main

ssssssssssssssssssessssssss

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CARDBOARD 3

An Economy Expansion Interface
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The "CARDBOARD/a" is an expansion inter-
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:-20^' is a registered trademark of Commodore

No. 57 - February 1983

MICRO

LANGUAGES

loop. If the key is a special case, EDIT
executes the corresponding special
function. Otherwise the key is added to
the FORTH screen and the video
screen. CASE structure allows EDIT to
be modified or expanded easily, yet ex-
ecutes quickly.

A two-key escape sequence is used
to add special functions, which do not
have Atari keys, to EDIT. The first
escape character starts the execution of
the FORTH word ESC. ESC, like EDIT,
uses a CASE statement to allow the
next key input to select a special func-
tion. Different classes of special func-
tions can be added easily to EDIT with
this technique.

This is one of my first APX fig-
FORTH applications and the expert
FORTH coder may notice how little the
stack is used as word inputs. Old pro-
gramming habits die hard! Even so,
there are only four important variables
used in EDIT. CLINE and CCHAR
maintain the current line and current
character position in memory and on
the text window display. SIDE keeps
track of whether the left side (SIDE = 0)
or the right side (SIDE = 1) of the
FORTH screen is displayed in the text

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Listing 1 (continued)

SCR #

(
1

CURSOR MOVEMENT PRIMITIVES )

MOVE-UP

CLINE 3 1 - 15 AND

CLINE :

WRITE-EXTRA ;

7 :

EUP

MOVE-UP

SCREEN-CURSOR ;

11 :

UP-CURSOR

SCREEN-CURSOR

EUP ;

15 -

SCR #

(
1

CURSOR MOVEMENT PRIMITIVES )

T .

MOVE-DOWN

CLINE 3 1 + 15 AND

CLINE 1

WRITE-EXTRA ;

7 :

DOWN

MOVE-DOWN

SCREEN-CURSOR ;

11 :

DOWN-CURSOR

SCREEN-CURSOR

DOWN ;

15 -

SCR #

(

EDITOR PRIMITIVES )

RETURN

SCREEN-CURSOR

SIDE 3 IF 32 ELSE ENDIF

CCHAR 1

DOWN ;

a :

EXIT

FLUSH

1 STOP 1 ;

12 :

EABORT

EMPTY-BUFFERS

14
IS -

1 STOP 1 ;

SCR #

(

EDITOR PRIMITIVES )

ENEXT

FLUSH

SCR 3 1 + SCR 1

EREAD

DISPLAY !

a :

ELAST

FLUSH

SCR 3 1 - SCR !

EREAD

12
1 3

DISPLAY :

15 -

SCR #

(

1
^ .

EDITOR PRIMITIVES )

ADDR

CLINE 3

SCR 3 (LINE) DROP

CCHAR 3 + ;

7 :

ADDKEY

DUP ADDR C !

CURSOR EMIT

RIGHT ;

12 :

CHANGE-SIDE

SIDE 3 1 XOR SIDE !

DISPLAY ;

15 -

- >

^ — )

( Ad.-just current line, 0-15 )

( Save - wraparound by AND )

< Add e>;tra line at bottom )

( ___ )

( Move Lip the di spl ay )

< Inverse video cursor pos )

( Restore current cursor )
( move Lip, new cursor )

( )

( Move down a line, 0-15 )

< Save new, wraparound by AND )
( Add extra te;:t line )

( )

( Move down a line )

( Set new cLtrsor video pos )

( )

< Restore vi deo cursor pos )

i Move down , set new crursor )

( )

( Restore cursor vi deo )

( Get beginning of line >

( Set as the cLirrent char )

( Move down )

( )

( Force di sk output d+ update
( Set editor stop flag )

( )

( Scratch updated buffers )
( Set editor stop flag )

( )

< Write out updated buffers )

( Ne;;t screen, no error check )
( Read the FORTH screen )

i Display, and edit )

/ )

'. Wri te out updated buffers )

'. Last screen, no error check )

< Read the FORTH screen )
( Display, and edit )

( )

( Get the current line number )
( Get the memory address )
( Add the current char pos )

( )

( Store a copy in memory text )
( Output char to vi deo screen )
< Move right for next )

( .)

( Flip LSB: fel, 1 legal values )
( Display, set CCHAR to start )

MICRO

No. 57 - February 1983

Listing 1 (continued)

SCR #

(
1

2 :

EDITOR PRIMITIVES )

INSERT-CHAR

( end-o-f-1 ine )

ADDR SWAP CCHAR 3 -

( Current addr, chars to move )

SWAP OVER + SWAP

( End of line, tt to move >

-DIJP IF

( If any chars to move right )

( For each char to move over )

DUP 1 - C3 OVER CI

( Store previous toward end )

1 -

( Next one closer to blank )

LOOP

( Until space opened in line )

ENDIF

BL SWAP C! ;

< Fill for space )

12 :

INSERT

( ,

SIDE 3 IF 63 ELSE 31 ENDIF

( Set end of line limit )

INSERT-CHAR WRITE-LINE

( Insert blank, output line >

CURSOR SCREEN-CURSOR ; — 5

C Set the cursor )

SCR #

(
1

EDITOR PRIMITIVES )

DELETE-CHAR

( end-of-line >

ADDR SWAP CCHAR 2 -

( Get addr, # chars to move )

-DUP IF

( If any chars to move left )

i For each moving character )

DUP 1 + C3 OVER C!

( Move right to left )

1 +

( Next address in line )

LOOP

ENDIF

BL SWAP C ' !

( Insert blank at end of line )

12 :

DELETE

( )

SIDE 3 IF 63 ELSE 31 ENDIF

< Determine end char of line )

DELETE-CHAR WRITE-LINE

( Delete current char, outut )

CURSOR SCREEN-CURSOR ; — >

( Reset cursor )

SCR «

(

1
2 :

EDITOR PRIMITIVES )

L-A

( addr )

3
4
S :

SCR S (LINE) DROP ;

( Get the address of start )

DELETE-L

( )

CLINE S> L-A SAV-BUF 64 CMOVE

( Save current in SAV-BUF )

15 CLINE 3 - IF

( If not the last line >

15 CLINE 3 DO

( For each line above current )

I 1+ L-A I L-A 64 CMOVE

( Move line one toward line«0 )

LOOP

ENDIF

12
13
14 :

15 L-A 64 BLANKS ;

( Blank line « 15 )

DELETE-LINE

( )

DELETE-L DISPLAY ; — >

( Delete and display )

SCR #

(

1
2 :

EDITOR PRIMITIVES )

INSERT-L

)

15 CLINE 3 - IF

If not the last line )

CLINE 3 15 DO

Start at the end of screen )

I 1 - L-A I L-A 64 CMOVE

Shuffle lines to end )

-1 +LOOP

Move toward current )

ENDIF

CLINE 3 L-ft 64 BLANKS ;

Blank current line )

9 :

INSERT-LINE

( )

INSERT-L DISPLAY ;

Insert blank line, display )

12 :

PUT-LINE

( )

INSERT-L

< Insert a blank line )

SAV-BUF CLINE 3 L-A 64 CMOVE

( Restore deleted line )

DISPLAY ; — >

< Display )

SCR «

(

EDITOR PRIMITIVES )

TAB

( )

2 DO

( Tab spaces only 2 for me )

RIGHT-CURSOR

< Simulate moving cursor )

5
6
7 :

LOOP ;

DEL

( >

LEFT-CURSOR BL DUP ADDR C!

( Move left and blank mem )

CURSOR EMIT SCREEN-CURSOR ;

( Echo to screen )

11 :

CLEAB-SCR

( )

16 DO

( For all 15 lines in screen )

I L-A 64 BLANKS

< Blank memory text )

LOOP

DISPLAY ; — >

( Display results )

^^M LANGUAGES

window. Finally, STOP is the exit flag
used in the main loop (0 = continue,
l = stop).

EDIT implements the following
special function keys of the Atari 800:

Command

[delete]

CTRL/ [delete]

SHFT/ [delete]
CTRL/ [insert]

SHFT/ [insert]

CTRL/ [clear]

SHFT/[clearl

CTRL/ [right]

CTRL/Jleftj

CTRL/[up]

CTRL/ [down]

RETURN

TAB

Function

Delete character be-
fore cursor
Delete current char-
acter, shrink line in
text window
Delete current line,
move rest up one line
Insert space at cur-
sor, expand line in
text window
Insert new line at
cursor, line 15 is lost
from the display but
saved in a buffer for
the "ESC P"
command
Clear the text
window
Clear the text
window

Move cursor right
within text window
Move cursor left
within text window
Move cursor up
within text window
Move cursor down
within text window
Advance to the first
character of the next
line

Move two characters
right

Only the text window is affected by
these special function keys.

The following functions are imple-
mented as two-key escape sequences:

Command Function

ESC E Exit the editor, writing the

edited screen to disk
ESC A Abort the edit session, no

change to the disk screen
ESC N Save the current screen,

edit the next screen
EXC L Save the current screen,

edit the last screen
ESC S Switch FORTH screen

sides in the text window
ESC P Put down (insert) the last

line deleted

The escape sequence method was
chosen in order to leave the normal and

No. 57 - February 1983

MICRO

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MICRO

No. 57 - February 1983

LANGUAGES

Listing 1 (continued)

SCR # 84

( ESCAPE KEY PROCESSOR >

KEY DOCASE

( Do case on the next key )

SCR

9
10
1 1
12
13
14
15

S3 CASE CHANSE-SIDE ENDCASE < ESC S

78 CASE ENEXT

76 CASE ELAST

69 CASE EXIT

65 CASE EABQRT

30 CASE PUT-LINE

ENDCASE ( ESC N

ENDCASE ( ESC L

ENDCASE ( ESC E

ENDCASE ( ESC A

ENDCASE ( ESC P

change video side )
edit next screen )
edit last screen )
exit editor )
abort edit session )
put down deleted line

BEEP ENDCASES

i else signal Vtey error )

# 85

•; SCREEN EDITOR DEFINITION )

: EDIT
SCR !

EREAD DISPLAY
STOP :

BEGIN
KEY DOCASE

28 CASE UP-CURSOR ENDCASE

29 CASE DOWN-CURSOR ENDCASE
31 CASE RIGHT-CURSOR ENDCASE

30 CASE LEFT-CURSOR ENDCASE
155 CASE RETURN ENDCASE

( screen# )

( Save EDIT screen number )
( Read and display screen )
( Clear stop -flag to -false )

( Begin editing )

( Get a key and process )

ATARI up arrow )

ATARI down arrow )

ATARI right arrow )

ATARI le-ft arrow )

ATARI return key )

SCR # 06

( SCREEN EDITOR DEFINITION )
1

2 255 CASE INSERT ENDCASE

3 254 CASE DELETE ENDCASE

4 157 CASE INSERT-LINE ENDCASE

5 156 CASE DELETE-LINE ENDCASE

6 126 CASE DEL ENDCASE

7 127 CASE TAB ENDCASE

8 125 CASE CLEAR-SCR ENDCASE
9' 27 CASE ESC ENDCASE

DUP ADDKEY ENDCASES
STOP 3
UNTIL

XGR ;

( ATARI
( ATARI
( ATARI
( ATARI
( ATARI
< ATARI

CTRL/ INSERT key )
CTRL /DELETE key )

)

SHIFT/ INSERT key

SHIFT/DELETE key )

DELETE key )

TAB key )
( ATARI CTRL/CLEAR key )
( Enter escape key -function )
'. else addkey to text )
( Check i-f stop -flag set )
( Edit until stop is true )

< Clear screen, goto FORTH )

control keys (graphics) available for
FO_RTH screen text.

As a final note, most versions of fig-
FORTH do not include a CASE state-
ment. However, unlike languages such
as BASIC or FORTRAN, FORTH may
be extended to include new control
structures. EDIT uses a set of CASE
words defined by Dr. C.E. Eaker,
orginally written for a 6800 FORTH
system {FORTH Dimension, Volume
II, Number 3, pp. 37-40). Only the
word names were changed when using
this CASE statement. The actual
definitions were compiled and ex-
ecuted the first time. Applications
written in high-level FORTH (no code
words) can usually be transported be-
tween FORTH systems, regardless of
the processor type.

Conclusion

EDIT is my first large application
with the APX fig-FORTH implementa-
tion. While EDIT probably is not as
efficient as possible, it was written and
debugged in less than 15 hours. Any
language that allows a large application
to be rapidly and logically imple-
mented during the learning process cer-
tainly deserves attention! Many well-
designed concepts are at work in
FORTH and all programmers should
consider FORTH as an alternative to
BASIC.

The author may be contacted at 7659 West
Fremont Ave., Littleton, CO 80123.

iMCftO

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No. 57 - February 1983

MICRO

LANGUAGES

APPLE Pascal
Hi-Res Screen Dump

by Robert D. Walker

A Pascal procedure to dump the
high-resolution graphics screen
to your printer.

SCREENDUMP

requires:

Pascal

Epson with Graftrax

Many machine-language subroutines
have been written to dump the Apple
high-resolution graphics to the Epson
MX-80 printer. I have not found, how-
ever, any subroutine specifically written
for Apple Pascal. If you own an Epson
MX-80 (with Graftrax) and want a hard
copy of Turtlegraphics, the following
Pascal procedure should prove handy.

The procedure in listing 1 takes ad-
vantage of Pascal's ability to declare
variant records. The type WIRES
associates eight boolean variables with
eight bits in a byte. In fact, these eight
boolean variables occupy the same
memory location as the byte. Each
boolean variable represents one wire on
the printhead. If the boolean variable is
true, the printing wire is fired, other-
wise it is not.

I encountered one problem during
the testing of this procedure. The
intrinsic WRITE procedure does not
allow all character codes to be passed to
the printer. This problem is cir-
cumvented by using the low-level pro-
cedure UNITWRITE (see pp. 41-42 of
the Apple Pascal Language Reference
Manual] .

The SCREENDUMP procedure has
the following form: SCREENDUMP
(LEFT, RIGHT, BOTTOM, TOP,
LMARGIN)

LEFT = left X position to be printed
RIGHT = right X position to be printed
BOTTOM = bottom Y position to be

printed
TOP = top Y position to be printed
LMARGIN = number of spaces in left

margin
[Note: both Y values are rounded to the
next lower integer evenly divisible by
eight.]

Using SCREENDUMP is simple. I
have included a sample printout and a
short program that demonstrates its
use. The procedure is easy to use and

there is no need for error checking. It is
the programmer's responsibility to en-
sure that all parameters are within the
proper range.

I have used this procedure in many
programs involving Turtlegraphics. Be-
cause of the popularity of the Apple II
and the Epson MX-80, this procedure
should find a place in many subroutine
libraries.

You may contact the author at 2850 Delk
Rd., Apt. 2B, Marietta, GA 30067.

Figure 1: Sample Ouptut From SCREENDUMP

MICRO

No. 57 - February 1983

LANGUAGES

Listing 1: SCREENDUMP

PROGRAn SAnPLEUSEOFSCREENDUnP; (t SAHPLE PROGRAH USING SCREENDUHP I)
USES TURTLEGRAPHICS;
VAR DISTINC: INTEGER;

PROCEDURE SCREENDUNPILEFT, RIGHT, BOTTGH, TOP, LNARGIN: INTEGER!;
(titttttlllttlltttttlllltllttltlllllltttttllllttllltllttttllltllttlltllt)

(It It)

(tt THIS PROCEDURE DUI1PS THE APPLE HIRES SCREEN TO THE EPSON m-it III
(If PRINTER EQUIPPED NITH GRAFTRAX. TURTLEGRAPHICS PROCEDURES AND tl)
(It FUNCTIONS ARE USED. It)

(tl II)

(tt R. NALKER 7/82 tl)

(It BARIETTA, GA ttl

(It It)

(tttttttttltlttttlltttlttttttttttttttltltttttlttllltttttttlttltltttltltl)

TYPE BVTE=8..255;

(t USE VARIANT RECORD TO ASSOCIATE PRINTING HIRES NITH iilE «)
mRES=PACKED RECORD CASE BOOLEAN OF

TRUE: (BO: PACKED ARRAY [0.. 71 OF BOOLEAN);
FALSE; (BY: BYTE)
END;

VAR I,1(,YC0ARSE,YFINE: INTEGER;

BITIHAGE; PACKED ARRAYI8. .288] OF BYTE;
PRINTCODE; PACKED ARRAY[1..4] OF BYTE;
N: yiRES;

BEGIN (I SCREENDUHP t)

il SET LINE SPACING TO 24/214" t)

PRINTCODE! 1];=27; PRINTC0DE[2h=51; PRINTC0DE[3h=24;

UNITNRITE(4,PRINTC0DEtl],3,«,12);

(I PRINT SCREEN I)

FOR YCOARSE:= (TOP DIV B) DONNTO (BOTTOH DIV 8) DO

BEGIN

(t HAKE LEFT MARGIN I)

PRINTC0DE[1]:=32;

FOR I:=l TO LBARGIN DO UNITNRITE(4,PRINTCOOE[1],1,0, 12) ;

(t ASSEHBLE ONE LINE OF BIT IHAGES ti
FOR ](;=LEFT TO RIGHT DO
BEGIN
FOR YFINE;=8 TO 7 DO N.BQ[YFINE]:=SCREENBIT(](,YCOARSEIB+YFINE);
BITIHAGE[1I]:=H.BY
END;

(t TELL PRINTER HON HANY DOTS IN LINE t)
PRINTCODE! 11: =27; PRINTC0DEI2l!=75;
PRINTC0DEI31:=(RIGHT-LEFTtl) HOD 254;
PRINTC0DEC41:=(RI6HT-LEFTtl) DIV 254;
UNIT«RITE(4,PRINTC0DE[11,4,8,12);

il SEND ONE LINE OF BIT II1A6ES TO PRINTER I)
BITII1AGE[RIGHTtl]: = l«; (t LINEFEED t)
UNITHRITE(4,BITinA6E[LEFTl,(RlGHT-LEFTt2),«,12)
END;

(t RESET PRINTER t)
PRINTC0DEn]:=27; PRINTC0DEI2]:=44;
UNITHRITE(4,PRINTC0DE[11,2,8,121

END; (t SCREENDUHP t)

Listing 1: SCREENDUMP (continued)

BEGIN (I HAIN PROGRAH I)

(t DRAN PICTURE t)

INITTURTLE;

PENCOLOR(HHITE);

DISTINC:=1;

REPEAT

nOVE(DISTINC);

TURN(91);

DISTINC:=DISTINCtl
UNTIL DISTINC=300;
VIEKP0RT(74,2«3,14,32I;
FILLSCREENIBLACK);
PENCOLOR(NONE);
nOVETO(B4,20);
HSTRINSC SAHPLE SCREENDUHP');

(t CALL SCREENDUHP II
SCREEHDUHP(»,279,iJ,191,17)

END.

/MCftO

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LANGUAGES

An Introduction to FORTH

by Ronald W. Anderson

The author gives a brief
introduction to the FORTH
language, including a discussion
of Reverse Polish Notation, word
definitions, and stacic
manipulation.

FORTH was the result of the old adage
that "necessity is the mother of inven-
tion." Charles Moore developed
FORTH as a tool to help him program
computers more quickly than he could
with an Assembler.

If you have used a Hewlett Packard
calculator, you are familiar with
Reverse Polish Notation. FORTH
works with this notation exclusively.
Reverse Polish works well with a stack
structure. HP used it to simplify the
use of their calculators. The difference
between Reverse Polish and ordinary
algebraic notation may be seen in the
way you key a simple problem into
calculators that use these two nota-
tions respectively.

Algebraic

2 -H 2 =

2x3-1-4x5 =
(2-1-3) X (4-1-5) =

Reverse Polish

2 (enter) 2 +

2 (enter) 3x4 (enter) 5 x +

2 (enter) 3 -(- 4 (enter) 5 -(- x

The second and third problems
above are done in exactly the same
way; in algebraic notation, parentheses
are necessary for one case but not the
other, since multiplication takes
precedence over addition. When using a
Reverse Polish calculator, E^^^ER puts
the first argument on the stack. The
operator -(- or x , for example, puts the
second number on the stack and oper-
ates on the top two numbers, removing

the two numbers that were there and
leaving the result on top of the stack.
(In the case of the calculator, the top
item on the stack is always displayed.)
With this notation, you can put a group
of intermediate results on the stack and
then perform the final operations.
Though the idea might seem a bit
strange at first, most HP users will
testify that the operations may be per-
formed with little or no thought.

Several years ago, Consumei's
Report did a review of all the calcu-
lators available. They downgraded the
HP severely because of the "strange
notation." In a note a few issues later,
they did a reverse. It seems that every-
one who used the calculators eventu-
ally wound up looking for the HP
because it was easier to get the correct
answer on it.

FORTH, as you may have realized
by now, relies heavily on a stack for all
calculations. All of FORTH' s instruc-
tions in some way manipulate the in-
formation on the stack. FORTH in-
structions are called "words." A word
is defined by a "colon definition." A
word may have any combination of
ASCn characters as its name. "." is a
FORTH word meaning the same thing
as PRINT in BASIC. If you typed in the
instructions:

2 2*. (return)

FORTH would respond with:

4 OK

All FORTH words or instructions
must be separated by spaces. When
FORTH sees a literal number, it auto-
matically puts it on the stack, so an
equivalent of the (enter) from the
calculator is not necessary. (The space
after the number tells FORTH that the

number is complete.) Of course the
"*" means multiply, and the "."
means to print the result. Printing a
result removes it from the stack.
Assuming the stack was empty at the
start of the above sequence of instruc-
tions, it would be empty at the end.
"OK" is FORTH's analog of READY in
BASIC. Shown in figure 1 are the con-
tents of the stack, as each item in the
line above is encountered.

Figure 1

TOP 2

(empty)

OF -* (empty)

STACK

Now, let's define a word:

: SQUARE DUP ♦ ;

The word defined with a colon defini-
tion is SQUARE. It will square the
value on the stack. Now, if you type 2
SQUARE . (return) FORTH will put 2
on the stack. DUP is a FORTH word
that will push a DUPlicate of the top
item Onto the stack. " * " multiplies the
top two items on the stack and leaves
the result on top. 2 SQUARE . will
therefore result in the value 4 being
printed to the terminal. Now, of
course, if you typed '5 SQUARE .' you
would get 25 on the terminal. Further,
the result of SQUARE does not need to
be printed out. It could just as well be
left on the stack for use by another
calculation. You could type:

3 SQUARE 4 SQUARE + . (RETURN)

The result would be 9 -(- 16 or: 25 OK

MICRO

No. 57 - February 1983

LANGUAGES

The definition of SQUARE is com-
prised of just two other words, DUP
and *. The semicolon terminates the
word definition.

Figure 2 shows a colon definition of
a working square root function. First, a
couple of variables are declared. They
hold the number for which the square
root is to be found, and for an inter-
mediate GUESS or trial square root. The
algorithm, called Newton's method,
divides the number by a guess, and aver-
ages the result with the guess to make a
new guess. The process is repeated un-
til the new guess and the old guess are
either equal, or differ by 1 . (Remember,
this is integer arithmetic. The result for
some numbers will alternate between
two numbers that differ by 1; for others
it will reach a constant value.)

SQRT expects the value of the
number to be on the stack when SQRT
is called. The number will be used
several times in successive passes
through the loop, so it is immediately
stored in the variable NUMBER. Nam-
ing a variable places its address on the
stack. The word '!' makes FORTH use
the top item on the stack as a pointer
for a place to store the second item on

Figure 2

VARIABLE GUESS
VARIABLE NUMBER

SQRT
NUMBER ! 2 GUESS !
BEGIN NUMBER @ GUESS
GUESS @ -t- 2 / DUP
GUESS @ SWAP GUESS !
- ABS 2 < UNTIL
GUESS @ ;

the stack. Remember that you are
usually dealing with 16-bit words. 2
GUESS ! puts 2 on the stack and stores
it in the variable GUESS. BEGIN
signals the start of a loop that ends at
UNTIL. Within the loop, NUMBER
and GUESS are fetched. @ has the
reverse effect of !; it uses the top item
on the stack as a pointer to a variable,
and replaces the pointer value with the
value of the variable on the stack.

Next, the word 7' divides NUM-
BER by GUESS; the result remains on
the stack. Now GUESS is fetched again
and added to the result. 2 / divides the
sum by 2 and you have averaged the

result of the divide with the original
guess, so the new guess is now on the
stack. DUP duplicates the new guess
on top of the stack, and GUESS @ puts
the old one on top. Now you want to
save the new guess in GUESS, but it is
second on the stack, so use SWAP to
get it on top and then GUESS ! to put it
in GUESS. Now you have the new
guess and the old guess as the two top
items on the stack so subtract and take
the absolute value of the difference ( -
ABSj. You must set up a comparison
that will leave FALSE (0) on the stack
until you want to exit the loop. 2 <
UNTIL compares the value on the
stack with 2 and leaves TRUE when the
value is less than 2 (0 or 1|. At that
point the loop is done and you simply
pull the last guess as the result and
return with the result on the stack.

It is my understanding that an avid
FORTH fan frowns on the use of vari-
ables if it can be avoided. He would
probably figure out a way to keep both
GUESS and NUMBER on the stack (as
nameless values) and manipulate the
values with DUP, ROT, and OVER,
words that move the top values around
in various ways. I believe such code.

' ^injf fy'ff M 1

• 1 Ik

u^o^i^^iAdJ

THE PROFESSIONAL'S CHOICE
FORTH — A Tool for Craftsmen!

It has been said that if Chippendaie had made programs he would
have used FORTH as his tool. If you want to learn how to program,
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Dealer inquiries invited.

No. 57 - February 1983

MICRO

LANGUAGES

though perhaps a bit more efficient, is
too hard to follow. The use of variables
with fetch and store instructions makes
the program much more readable.

Now let's define a third word,
HYPOTENUSE, that will put the first
two together.

: HYPOTENUSE

SQUARE SWAP SQUARE + SORT ;

HYPOTENUSE is called with the
length of the two sides of a right
triangle on the stack. It returns the
length of the hypotenuse.

3 4 HYPOTENUSE . 5 OK

5 12 HYPOTENUSE . 13 OK

100 100 HYPOTENUSE . 141 OK

The above example shows how to
first define low-level words and then
use them to define higher-level words.
A FORTH program is built like this,
starting with low-level word defini-
tions, and continuing with higher- and
higher-level words, until very few words
can be combined to accomplish a task.

The trick of writing programs in

FORTH is simply to keep track of what
is on the stack at every point in the pro-
gram. This is facilitated by keeping
word definitions short. A bit of code
that leaves a data value on the stack
somewhere in the program may do no
harm, but if it is in a loop that repeats
many times, it will eventually cause
the stack to overflow and crash the pro-
gram. Code that removes more from the
stack than it puts on causes a STACK
UNDERFLOW error and most FORTH
implementations will tell you so.

Actually, the previous discussion is
a bit of an oversimplification, since
FORTH actually uses two stacks — the
parameter stack and the return stack.
The return stack is used to keep track
of the program flow from colon defini-
tion to colon definition, and it is usually
transparent to the user. Advanced tech-
niques may involve using words to
manipulate the return stack, as well.

FORTH has a core of standard
words for mathematical operators,
data-handling words, and decision
making. One of the differences among
the FORTH implementations is how
many core words are implemented in
assembler, as opposed to word defini-

tions in FORTH. Assembler-defined
words generally run faster than the
FORTH-defined words. Also, the main
part of FORTH will be smaller if more
of the core is implemented in
assembler.

The normal math functions in
FORTH are based on 16-bit integer
arithmetic, so numbers have the range
of 32767 to -32768. The implemen-
tations discussed in the companion
article (pg. 62] have additional standard
FORTH words defined that allow
manipulation of larger integer
numbers, such as D* for double preci-
sion multiply, etc. You can write a
floating-point math package in FORTH
if it is required for your applications.
You can tailor the package to your
needs, so that you don't have to suffer
with the slow calculations of a 12-digit
floating-point math if you need only six
or seven digits. Such routines have
been published and some are commer-
cially available.

The author may be contacted at 3540
Sturbridge Ct., Ann Arbor, MI 48105.

/MCftO

Perry PerjpIieraIs RepaIrs KIMs!!

(SYlVIs ANd AIMS Too)

• We will Diagnose, Repair, and Completely Test your Single Board Computer

• We Socket all replaced Integrated Circuits

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• Your repaired S.B.C. returned via U.P.S. — C.O.D., Cash

Don't delay! Send us your S.B.C. for repair today
Ship To: (Preferably via U.P.S.)

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6 Brookhaven Drive
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• Exact replacement for MOS/Commodore KIM-1 S.B.C.

• Original KIM-1 firmware — IK and 4K RAM versions

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Perry Peripherals is an authorized HDE factory service center.

Perry Peripherals carries a full line of the acclaimed HDE expansion components for you KIM, SYM, and AIM,
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more information write to: P.O Box 924, Miller Place, NY 11764, or Phone (516) 744-6462.

MICRO

No. 57 - February 1983

The 68000

DREAM MACHINE

WE (SORT OF) LIED:

Motorola has been promoting its advanced microprocessor
chip as a vehicle tor large, complex systems exclusively.
Now^, the 68000 does w^ork w^ell as the heart of big, complex
systems. But their promotional literature implies that one
can only build big, complex systems w^ith the 68000, and that
is dead wrong (in our opinion). Nevertheless, the public
(that's you!) perception of the 68000 tollow^s Motorola's line:
Big systems. Complex systems.

Our boards are not complex and not necessarily big (starting
at 4K). Our new^sletter is subtitled "The Journal of Simple
68000 Systems." But since the public has become condi-
tioned to the 68000 as a vehicle for FORTRAN, UNIX, LISP,
PASCAL and SMALLTALK people naturally expect all these
w^ith our $595 (starting price) simple attached processor.
Wrong!

We wrote our last ad to understate the software we have
available because we wanted to get rid of all those guys who
want to run (multi-user, multi-tasl<ing) UNIX on their Apple II
and two floppy disks. Running UNIX using two 143K floppies
is, well, absurd. The utilities alone require more than 5
megabytes of hard disk.

HERE'S THE TRUTH:

We do have some very useful 68000 utility programs. One of
these will provide, in conjunction with a suitable BASIC com-
piler such as PETSPEED (Pet/CBM) or TASC (Apple II), a five
to twelve times speedup of your BASIC program. If you have
read a serious compiler review, you will have learned that
compilers cannot speed up floating point operations
(especially transcendentals). Our board, and the utility soft-
ware we provide, does speed up those operations.

Add this line in front of an Applesoft program:

5 PRINT CHR$(4);"BLOADUTIL4,A$8600":CALL38383

That's all it takes to link our board into Applesoft (assuming
you have Applesoft loaded into a 16K RAM card). Now run
your program as is for faster number-crunching or compile it
to add the benefit of faster "interpretation". Operation with
the Pet/CBM is similar.

68000 SOURCE CODE:

For Apple II users only, we provide a nearly full disk of un-
protected 68000 source code. To use It you will have to have
DOS toolkit ($75) and ASSEM68K ($95), both available from
third parties. Here's what you get:

1) 68000 source code for our Microsoft compatible floating
point package, including LOG, EXP, SQR, SIN, COS, TAN,
ATN along with the basic four functions. The code is set up to
work either linked into BASIC or with our developmental
HALGOL language. 85 sectors.

2) 68000 source code for the PROM monitor. 35 sectors.

3) 68000 source code for a very high speed interactive 3-D
graphics demo. 115 sectors.

4) 68000 source code for the HALGOL threaded interpreter.
Works with the 68000 floating point package. 56 sectors.

5) 6502 source code for the utilities to link into the BASIC
floating point routines and utility and debug code to link into
the 68000 PROM monitor. 113 sectors.

The above routines almost fill a standard Apple DOS 3.3 flop-
py. We provide a second disk (very nearly filled) with various
utility and demonstration programs.

SWIFTUS MAXIMUS:

Our last advertisement implied that we sold 8MHz boards to
hackers and 12.5MHz boards to businesses. That was sort of
true because when that ad was written the 12.5MHz 68000
was a very expensive part (list $332 ea). Motorola has now
dropped the price to $1 1 1 and we have adjusted our prices ac-
cordingly. So now even hackers can afford a 12.5MHz 68000
board. With, we remind you, absolutely zero wait states.

'Swiftus maximus'? Do you know of any other
microprocessor based product that can do a 32 bit add in 0.48
microseconds?

AN EDUCATIONAL BOARD?

If you want to learn how to program the 68000 at the
assembly language level there is no better way than to have
one disk full of demonstration programs and another disk full
of machine readable (and user-modifiable) 68000 source
code.

Those other 'educational boards' have 4MHz clock signals
(even the one promoted as having a 6MHz CPU, honest!) so
we'll call them slow learners. They do not come with any
significant amount of demo or utility software. And they com-
municate with the host computer via RS 232, 9600 baud max.
That's IK byte/sec. Our board communicates over a parallel
port with hardware AND software handshake, at 71 K
bytes/sec! We'll call those other boards handicapped
learners.

Our board is definitely not for everyone. But some people find
it very, very useful. Which group do you fit into?

DIGITAL ACOUSTICS

1415 E. McFadden, Ste. F

Santa Ana, CA 92705

(714) 835-4884

Apple. Applesoft and Apple II are trademarks of Apple Computer Company. Pet Is a trademark of Commodore Business Machines. ■

No. 57 - February 1983

MICRO

LANGUAGES

FORTH for the 6809

by Ronald W. Anderson

The various versions of FORTH
available for 6809-based
computers are discussed. These
include CCFORTH for the Color
Computer, fig-FORTH, and
several FLEX-based systems.

fig-FORTH

No discussion of FORTH would be
complete without mention of the
FORTH Interest Group (fig). Fig has
implemented FORTH for most of the
processors that are commonly used in-
cluding the 6800, 6809, 6502, and
68000. Source listings of fig-FORTH for
these processors are available from fig
for a nominal charge (it was around $15
when I bought it) .

The 6809 version is compatible at
the most minimal level with the FLEX
operating system. It is implemented as
(or includes) its own disk operating
system, accessing disk sectors directly.
Depending on the number of bytes per
sector, it utilizes four or eight sectors
to form a unit of memory called a
screen. A screen is a terminal screen
full of information, consisting of 16
lines of 64 characters. The FORTH disk
operating system is workable, but
primitive by present day standards.
There is no directory facility. Standard
practice is to use the first line of every
screen as a description of the contents,
a type of comment line. A FORTH
word will list the first lines of all the
screens, forming a directory of sorts.
What serves to make the use of this
disk operating system a bit more dif-
ficult, is that the sectors written by fig-
FORTH may not be accessed by or
through the FLEX operating system (ex-
cept through a sector dump utility) .

Included in the fig-FORTH system
is a line editor that allows you to access
and change information stored in
screens. Some of the more advanced
systems have a screen editor that is a bit
more convenient than the fig line editor.

When you write a program or ap-
plication, you edit some screens, put-
ting your word definitions on them.
You may at any time load a range of
screens, which causes them to be com-
piled so the program may be run.
Therefore, you can debug your program
interactively, ruiming and editing
screens alternately. There is a screen
buffer that can hold from two to several
screens, so they don't have to be writ-
ten to or read from disks for every
change. FORTH keeps track of whether
a screen has been updated, and won't
let it be overwritten in the screen buffer
without automatically rewriting it to
the disk. That is a very handy feature.

Fig-FORTH as supplied has the
source code for FORTH and some
FORTH screens that must somehow be
bootstrapped into the system to get the
editor working. The disk operating sys-
tem ties to FLEX and is compatible at
the disk driver level. I have the fig im-
plementation and have typed it in and
gotten it up and running. If you are new
to FORTH, however, I would not rec-
ommend going the fig route. However,
if you can learn FORTH first on another
system, the fig route is an inexpensive,
though time consuming, way to go.

FORTH from Talbot Microsystems

Ray Talbot, who wrote the fig im-
plementation for the 6809, sells an
implementation of FORTH through his
company, Talbot Microsystems. Tal-
bot's implementation, known as
tFORTH, offers features that make it
easier to use with FLEX. The disk con-
taining the FORTH compiler has
several tracks that are initialized in the
standard FLEX format. This allows the
user to have the FORTH compiler on
those tracks and to call it with a stan-
dard FLEX call. The user may put FLEX
itself, the necessary utilities to boot
FLEX, and perhaps some utilities such
as COPY, LIST, etc., on those tracks

also. The remainder of the disk is used
by FORTH directly as screen storage.

FORTH will access a second disk
drive when the screen number re-
quested goes beyond the range of those
numbers available on the first drive (a
handy feature) . There are some utilities
included in FORTH to do an index, list
screens over a range of specified num-
bers and list them formatted three to a
page for a printer. Other utilities are in-
cluded to copy one screen to another
and delete screens.

In addition to tFORTH, Talbot has
available an extended version called
tFORTH -I- , The added features are a
screen-oriented editor, a full 6809
assembler, a CASE statement, and
some additional data types such as
ARRAYS. Another program available
from Talbot is firmFORTH. firm-
FORTH allows you to shrink a finished
application program to a bare
minimum by including only the core
words that you have used in your ap-
plication. It eliminates everything else,
and generates only the necessary binary
code that you may bum into an
EPROM for a dedicated application, or
save on a disk for quick load and run.

XFORTH from Frank Hogg Labs

Frank Hogg Laboratories of
Syracuse, NY, also supplies a FLEX-
compatible version of FORTH called
XFORTH. XFORTH includes a com-
prehensive manual that contains a
tutorial on FORTH as well as an exten-
sive FORTH Glossary. This implemen-
tation comes complete with many
FORTH screens of application pro-
grams that aid you in using FORTH,
including a complete double- and
triple-precision integer arithmetic
package, an extensive Screen Editor,
and a complete 6809 assembler. Ver-
sions are provided for several terminal
models. With a bit of study, they may
be adapted to most any terminal that

MICRO

No. 57 - February 1983

LANGUAGES

allows computer-controlled cursor posi-
tioning, cursor home, and screen erase.
XFORTH varies from the fig stan-
dard disk operating system. It still uses
the screen concept, but an application
or program is kept in a standard FLEX
file. To load a particular application,
you load the FLEX file into a screen buf-
fer. Now screens in the program may be
accessed just as in standard FORTH.
When desired, the program may be
saved to a disk file. The advantage of
this file-handling method is that the
disk is completely compatible with
FLEX utilities to get a DIRECTORY,
LIST a file, COPY a disk, etc. It makes
life a bit easier for someone who uses a
number of different languages and
wants to keep things on a more com-
mon base.

CCFORTH from Frank Hogg Labs

Frank Hogg Laboratories also offers
a version of FORTH that runs on the
TRS-80 Color Computer. It uses the
TRS-80 disk operating system, so it is
not necessary to have FLEX on the CC
in order to use it. CCFORTH contains a
screen editor and some other features
that make it particularly well adapted
to use with the Color Computer. The
screen editor uses the four directional
arrow keys on the CC to position the
cursor in the command mode. You may
also delete characters or lines and in-
sert blank spaces or lines in this mode.
By typing ENTER, you enter the insert
mode; then you may type Ln lines of text
or insert characters Ln blank spaces.

I used this editor for entering and
testing the HYPOTENUSE program
described in the companion article (p.
). The three word definitions fit
nicely on one screen. To get into the
editor mode, type < screen number >
EDIT. When you are done, type
< screen number > LOAD, and your
newly defined words are added to the
dictionary. If you get any error
messages, you can FORGET SQUARE
(the first new word) and re-edit your
definitions. This process is repeated
until your program runs. Because of the
display width limitation on the CC,
CCFORTH screens are 32 lines of 32
characters rather than the standard 16
lines of 64 characters. I found I liked
that anangement better. The shorter
lines allow for better program phrasing.

Charles Moore, the inventor of
FORTH, has said that FORTH is about
as controversial as religion or politics.

He maintains that a good way to start
an argument among programmers is to
say "Boy, FORTH is a great language."
I have mixed feelings about FORTH; it
is difficult to learn, and reading some-
one else's program can be a problem
(though I am beginning to see that
FORTH programs can be readably writ-
ten. Keeping track of all the data
floating around on the stack can be
most frustrating, particularly to a
beginner. However, in spite of a few
misgivings, I never cease to be im-
pressed with how much you can do
with FORTH with so little source code!
My guess is that with equally well-
documented and formatted programs in
FORTH, Pascal, and BASIC, the
FORTH program will be considerably
shorter and will run considerably faster
than any of the others.

68'FORTH for 6809 available as a
printed listing from;

FORTH Interest Group

P.O. Box 1105

San Carlos, CA 94070
Write for their current catalog and
prices.

tPORTH, tFORTH-i-, and firmFORTH
available from:

Talbot Microsystems

1927 Curtis Ave.

Redondo Beach, CA 90278

tFORTH $100.00

tFORTH-i- $250.00

firmFORTH $350.00

(requires but does not include
tFORTH -h)

XFORTH, CCFORTH available from:

Frank Hogg Laboratories

130 Midtown Plaza

Syracuse, NY 13210

XFORTH $149.95

plus $2.50 shipping (huge manual)
CCFORTH $ 99.95

The author may be contacted at 3540
Sturbridge Ct., Ann Arbor, MI 48105.

iMCftO

BIOSTATISTICS III

giTCCN lEKIlDN CBHPMIim

WATANABE PLOTTER GRAPHICS

BIOSTATISTICS III is a combined stat-
istical analysis and graphical data
plotting software package . It covers a
comprehensive range of bivariate and
multivariate tests cominonly used in
enigi nee ring and the social and medical
sciences .

SPECIAL FEATURES:

1) Generates regression plots in screen
high resolution graphics and on the
Wantanabe WX 4671 plotter.

2) Stores data in standard DOS 3.3 text
files , easy to access from your own
software or data base.

3 ) Programs are written in Applesoft
Basic. Can be user modified.

4) Includes extensive data editing and
file manipulation facilities .

5 ) Tabulated data printouts and stat-
istical results.

STATISTICAL TESTS: GRAPHICS

STANDARD DEVIATION

PAIRED STUDENT (t) TEST

UNPAIRED STUDENT (t) TEST

WILCOXON PAIRED TEST

MANN-WHITNEY U TEST

A N V A (ONE AND TWO WAY)

LINEAR REGRESSION *

EXPONENTIAL REGRESSION *

POLYNOMIAL REGRESSION *

CURVILINEAR REGRESSION *

MULTIPLE REGRESSION

SYSTEM REQUIREMENTS:

Apple 2 plus with 48k RAM and two Disk
Drives. Also compatible with the Apple
3 in emulation mode.

The package includes documentation and
both program and data discs.

PRICE

$95.00

Personal checks, COD or P.O.* on
of f ical order forms , accepted .
California residents add 6% sales tax .

Write for more information or order
from 1

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Pft02 140

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No. 57 - February 1983

MICRO

P-LISP

You don't need to be great with
numbers to learn programming
in LISP. Because LISP uses words
instead ot numbers, so you can
start lO program logically with-
out v/orrying about math. For
those who require it the new
P-USP version 3. 1 supports tloat-
ing point math, Hi-res graphics,
trig tunctions and all disk tile
tunctions.

P-USP is sold with a tun, easy
to read Tutorial that teaches you
LISP with hands on experience
You need an Apple U® or II to
mn P-USP
Educators: USP Is a great teach-
ing language.

Write to us for special quantity
pricing.

single copy price

$149.95

(includes tutorial)

iSm

4005 Chestnut Street Philadelphia, PA 19104 215-387-1500
Toll Free (orders only) 800-523-0725

Apple II 11 IS a registered trademark ol Apple Computers Inc

MICRO

No. 57 ■ February 1983

LANGUAGES

The World According to LISP

by Steven Cherry

LISP has always been considered
a language for large computers.
In this introduction, learn about
LISP as it is implemented
on a microcomputer.

Many people who work with com-
puters believe LISP is a strange and
obscure language used only by mad
computer scientists who are locked
away in research laboratories or univer-
sities working in that nebulous field
commonly known as Artificial Intelli-
gence (AI) . Indeed, because LISP gener-
ally has been restricted to use only on
large computer systems, few have been
able to obtain exposure to this language
outside an AI or academic environ-
ment. However, with the introduction
of P-LISP for the Apple II, as well as
other LISP interpreters for other ma-
chines, this trend is rapidly changing.
For Apple owners, access to a compre-
hensive and quite powerful LISP inter-
preter is now at their fingertips. It is
therefore a worthwhile endeavor to
take a close look at LISP to see what
we've been missing for so long.

LISP stands for "LISt Processor." It
was developed by John McCarthy at
MIT in the late 1950's, originally as a
tool for mathematical research.
Because of its unique features, LISP
quickly caught on as the language of
choice for work in Artificial Intelli-
gence. Unlike Pascal or FORTRAN,
there is no real LISP standard. Today
LISP is available in various flavors,
such as INTERLISP, MACLISP,
MTSLISP, and, of course, P-LISP. How-
ever, all LISPs more or less look and act
the same and are descendants of Mc-
Carthy's LISP 1.5.

What makes this language so
unique? The major strengths and fea-
tures of LISP can be outlined as follows:

• LISP uses the same data structure to
represent both programs (actually
functions) and data. Since programs
and data are indistinguishable [as far
as the LISP interpreter is concerned),
it is relatively easy to write LISP pro-
grams that construct and execute
other LISP programs.

• LISP is interpreted, providing the
user with immediate response. The
interactive nature of LISP makes it
easier to develop and debug programs
and gives the user the feeling that he
is talking to the computer.

• LISP has a simple and uniform syn-
tax; there are only a few rules to
remember, and these quickly become
second nature. Moreover, LISP is in-
dependent of the details of the
machine on which it is running;
there is no need to deal with word
sizes, the lengths of variable names,
declarations, etc.

• LISP is ideal for applications requir-
ing symbolic manipulation because,
unlike BASIC or Pascal, LISP deals
with objects rather than strings,
records, variables, pointers, etc. All
of the bookkeeping necessary for
representing or manipulating these
objects is implicit in the language; for
example, a program to differentiate
polynomials might be a chore to
write in BASIC or Pascal, but is
relatively simple and straightforward
in LISP.

• LISP is a heirarchical language; LISP
programs are actually functions, each
constructed out of more primitive
functions. A LISP interpreter is little
more than a set of pre-defined func-
tions. It is thus possible to build en-
tire systems (for example, the pro-
gramming language Smalltalk) out of

LISP primitives, and other systems

on top of these, etc.
So the picture doesn't appear too
perfect, I must point out that, as with
any language, LISP has some draw-
backs as well. Chief among these is its
memory demands: this language is a
memory hog and, although it can fit on
a micro (P-LISP is roughly 14K in
length and supports about 80 functions),
this demand can be quite limiting,
depending on the specific application
involved. Performance is another fac-
tor; because LISP is interpreted, execu-
tion speed is much slower than that of a
compiled language such as Pascal
[however, some systems do have LISP
compilers available) . A third problem is
the simple syntax of LISP, which can be
a liability as well as an asset. It is quite
easy to write a LISP function that is so
hopelessly obscure as to baffle even the
person who wrote it.

The Structure of LISP

The basic unit of information in
LISP is the atom. There are liteial
atoms, which are represented as a se-
quence of alphanumeric characters
beginning with a letter, and numeric
atozns, which are simply numbers.
Thus, A, HELLO, PQR57, and WALRUS
are literal atoms, while 12 and - 56.87
are numeric atoms. 15AYT would not
be an atom. The sequence of characters
that denote an atom are called the
atom's piint name. For example, the
print name of atom DEF is the se-
quence of characters D, E, and F.

Atoms can be combined to form the
basic data structure of LISP, the list. A
list is simply a sequence of symbolic
expressions or s-exprs, bound by a pair
of parentheses, where a s-expr is de-
fined to be an atom or a list. So, (A B C)
is a list comprised of three s-exprs, the
atoms A, B, and C. Similarly, (HAIL

No. 57 - February 1983

MICRO

LANGUAGES

AND (WELL MET) ) is a list comprised
of three s-exprs — namely, the atom
HAIL, the atom AND, and the list
(WELL MET), which in turn is com-
prised of the two atoms WELL and
MET. A list may contain any number of
atoms or lists as its elements. Be aware
that the parentheses are not part of the
list; they are punctuation marks that
define the list [just as a pair of quotes
defines a string in BASIC).

At the heart of LISP is the evaluatoi.
Whenever you type something into
LISP, the interpreter tries to evaluate
what you typed in and return the result
(this is known as a READ-EVAL- PRINT
loop). If, for some reason, LISP cannot
evaluate your input, it will give you a
friendly enor message indicating where
it got stuck and why. Actually, enor
recovery in LISP is entirely
implementation-dependent; there is
nothing in the definition of the lan-
guage that specifically states what
course of action should be taken if an
enor condition arises.

The following rule is used for
evaluating lists: when you give LISP a
list to evalute, LISP treats the first ele-
ment of the list as the name of a func-
tion, and the remaining elements (if
any) as the arguments to the function.
So, if you type the list (A B C), LISP
will try to apply some function named
A to the arguments B and C. For exam-
ple, suppose you want to add two num-
bers together. In BASIC, you would
type something like PRINT 1 + 2 to add
1 and 2. In LISP, you can accomplish
this by typing (ADD 1 2). ADD is a
built-in function that takes two
arguments — namely, two numeric
atoms — and returns the sum of the
arguments (in this case 3). The value of
a s-expr is the value returned when the
s-expr is evaluated. So the value of
(ADD 1 2] is the atom 3.

What if you type in something that
doesn't make much sense, like [ADD 1)?
Since the function ADD expects two ar-
guments, you should get an enor mes-
sage. P-LISP will give the following:

** ERROR: TOO FEW ARGS **
ADD:: (1)

The first line of the message indicates
what's wrong, and the next line shows
the function and the list of arguments
LISP was working on when the error
occurred.

Atoms may have values associated
with them, just like a variable in
BASIC or Pascal can be assigned a

value. If you type an atom into LISP,
the interpreter will return the value of
the atom, if it has one. For example,
numeric atoms are defined to have
themselves as their value. The value of
the atom 3 is 3 (as you'd expect). If you
type 3 into LISP, you'll get back 3, the
same as if you'd typed [ADD 1 2). As a
general rule, literal atoms don't have a
value until they're given one. The value
cf a literal atom may be any s-expr.

One thing you can do with lists is
take them apart. The LISP function
CAR takes a list and returns the first
element of the list. If you type (CAR ' (A
B C) ) you get A as the value. When you
give LISP something to evaluate, of the
form (Function Argl Arg2 . . . Argn)
LISP first evaluates the arguments,
then applies the function to the argu-
ment values to return the final result.
For example, if the value of A is 1, and
the value of B is 2, then (ADD A B) will
return 3.

In the example for CAR above, the
quote tells LISP not to evaluate the
argument before applying the CAR func-
tion. In other words, if you didn't type
the quote, LISP would first try to evalu-
ate the s-expr (ABC), then apply CAR to
the result. With the quote, LISP applies
CAR directly to (A B C), returning A.

The LISP function CDR is the com-
plement of CAR. CDR takes a list and
returns that list minus the first ele-
ment. So, (CDR '(ABC)) returns (B
C). If you type (CDR '[HITHEREJ )
LISP gives NIL. NIL is a list containing
zero elements, or the empty list. Also,
NIL is represented by an empty pair of
parentheses, [ ). NIL is considered a
special element of LISP because it is
both a list and an atom. NIL has itself
as its value; i.e., the value of NIL
is NIL.

NIL also is used to represent the
truth value "false". As you'd expect,
there is an atom to represent the truth
value "true" — namely, T. The value
of T is T. NIL and T are the only literal
atoms built into LISP with predefined
values (actually, any non-NIL value in
LISP is considered to represent "true".
T is convenient because its value is
always guaranteed to be non-NIL) .

One area where T and NIL come in-
to play is with predicates. Predicates
are functions that perform a certain test
on their arguments and return T if the
argument passes the test and NIL if it
fails. One such predicate is ATOM;
ATOM returns T if its argument is an
atom, and NIL otherwise. For example,
[ATOM '(IM A LIST) ) returns NIL,

whereas (ATOM 'BOMB] returns T.
The s-expr (ATOM ( ) ) also returns T
(remember, ( ) is an alternate represen-
tation for NIL, which is an atom) .

Another important predicate is
NULL, which returns T if its argument
is NIL, and NIL otherwise. So, (NULL
'(8 9 10) ) returns NIL, but (NULL
[CDR '(BLEAT) ) ) returns T. LISP first
evaluates the arguments to a function,
then applies the function to the result.
In the above example, the argument to
NULL is the s-expr (CDR '(BLEAT) ).
LISP evaluates this and returns NIL,
which is then passed on to NULL. The
NULL of NIL is T, so T is returned as
the value of the entire s-expr.

Incidentally, CAR and CDR are the
only functions in LISP whose names
have nothing to do with their meaning.
Their names are derived from the hard-
ware on which the first LISP interpreter
was implemented: CAR stands for
"Contents of Address Register" and
CDR stands for "Contents of Decre-
ment Register." On some LISP systems
they have been given the more mean-
ingful names FIRST and REST; but for
the most part, their original names
have stuck.

In addition to functions that take
lists apart, LISP is supplied with func-
tions to put lists together. One of these
is the function CONS, for CONStract.
CONS takes two s-exprs and returns a
new list such that the first argument is
the CAR of the list and the second argu-
ment is the CDR of the list. For exam-
ple, (CONS 'THIS '[IS FUN) ) returns
(THIS IS FUN). Note that the CAR of
this list is THIS, and the CDR is the list
(IS FUN).

CONS puts things at the front of
lists. Another function, APPEND, puts
things at the end of lists. For example,
(APPEND '[THESE THAT) 'THOSE)
returns [THESE THAT THOSE).

Other functions used for building
lists include CONC and LIST. CONC
concatenates lists together and LIST
creates a list of its arguments. Some ex-
amples: (CONC '(I LISP] '[YOU LISP) )
returns (I LISP YOU LISP), and (LIST 'A
'B '(AND C) ) returns [A B (AND C) ).

I mentioned above that it is possible
to assign values to literal atoms. This is
done with the LISP fimction SETQ.
The first argument to SETQ is the atom
to be assigned a value and the second
argument is the value. An anomaly to
remember about SETQ is that the first
argument is not evaluated, but the sec-
ond argument is. For example, if you
want to assign the atom A the value

MICRO

No. 57 - February 1983

(WHO AM I), type (SETQ A '(WHO
AM I) ). Now whenever the atom A is
evaluated, the list (WHO AM I) would
be returned.

Although there is no string data
type in LISP, there are facilities to treat
atoms' print names as though they
were strings. One such facility is the
special kind of literal atom called the
string atom. A string atom is the same
as a literal atom in all respects, except
that its print name is delimited by a
pair of double quotes. Any character
may appear within the quotes (except a
double quote). For example, "THIS IS
A SINGLE ATOM" is a single atom
whose print name is the sequence of
characters between the double quotes.
String atoms allow you to create atoms
with "funny" print names; for in-
stance, "(" can be an atom [it has
nothing to do with the ( symbol used to
denote lists).

The LISP functions EXPLODE and
IMPLODE allow the user to manipu-
late print names. EXPLODE takes an
atom and returns a list of the characters
in the atom's print name,- thus, (EX-
PLODE 'TNT) returns the list (TNT).
IMPLODE does the reverse of EX-
PLODE; it takes a list of atoms and

returns an atom whose print name is
the compression of the atoms in the
list. For example, (IMPLODE '(N E U T
RON)) returns the atom NEUTRON.
Of course, LISP wouldn't be much
fun or very useful unless you were able
to create your own functions. The LISP
function DEFINE is used to define func-
tions. The general form of a function
definition is as follows:

(DEFINE (function-name (LAMBDA
(fornnal arguments)

function-body

The function-name is a literal atom,
which is what the function will be
called. A LAMBDA-expiession follows
the function-name; all user-defined
functions must be some form of
LAMBDA-expression. The second part
of a LAMBDA-expression (following
the atom LAMBDA] is a list of atoms
that are the function's foimal
aiguments (if the function takes no
arguments, the list is NIL). This list
tells LISP the number of actual
arguments the function takes, and how
these arguments are referred to in the
body of the function [the example

IHIH LANGUAGES |

below will help clarify these points).
The last part of the LAMBDA-expres-
sion is the actual body of the function
and is a s-expr whose value will be
returned as the value of the function.

As an example, suppose you want a
function that returns the second ele-
ment of a list; that is, if you gave the
function the list [A B C), you want the
function to return B. Call this function
SECOND:

(DEFINE (SECOND (LAMBDA (L)
(CAR (CDR L) )
)))

L is the formal argument of SECOND.
When SECOND is invoked, L is bound
(SETQed) to the value of the actual argu-
ment and the function body (the CAR
of the CDR of L) is evaluated. For ex-
ample, if you type [SECOND '[ABC) ),
L is bound to the list (ABC), and CAR
(CDR L) ) is evaluated, returning B.

Whenever a user-defined function (a
LAMBDA-expression) is invoked, a
local envhonment for the function is
created consisting of the formal argu-
ments of the function and the values
they are bound to (known as LAMBDA-
binding] at the time of the invocation.

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LANGUAGES

This local environment remains in ef-
fect until the function is exited. At that
time, the environment is destroyed and
the next most recent environment b
comes the "current" environment. The
highest-level environment (the one in
effect before any functions are invoked)
is called the global environment.

Suppose you type (SETQ L '(THIS
BETTER WORK) ) into LISP. The
global value of L is now set to the list
[THIS BETTER WORK). If you type
(SECOND '(WHOS ON FIRST) ), a
local environment for SECOND is
created in which a local L is bound to
the list (WHOS ON FIRST). The func-
tion body is then evaluated. When the
function is exited, the local environ-
ment is destroyed and the value of the
function body, the atom ON, is re-
turned. If you now type L you get what
you had before: (THIS BETTER
WORK), which is the global value of L.

One of the nicer features of LISP is
that it allows the definition of recursive
functions. A recursive function is a
function that is defined in terms of
itself. A perfect example is the factorial
function, which is defined as follows:

n! = 1 if n =

n * (n- 1)! otherwise

This, function can be represented very
nicely in LISP:

(FACTORIAL (LAMBDA (N)
(COND
((EQUAL N 0) 1)
(T (MULT N (FACTORIAL (SUB N 1) ) ) )

COND is the LISP CONDitional
construct and is analogous to the IF-
THEN-ELSE construct in BASIC or
Pascal. The form of the COND is as
follows:

COND (el si)
(e2 s2)

(en sn) )

which can be thought of as meaning

IFe1 THEN s1
ELSE IF e2THEN s2
ELSE IF e3 THEN s3

ELSE IF en THEN sn
ELSE NIL

Each e 1 is evaluated until one evaluates
to a non-NIL value. The corresponding
si is then evaluated and returned as the
value of the COND. If all of the ei eval-
uate to NIL, then COND returns NIL.

In the FACTORIAL function above,
the COND returns 1 if N is equal to 0.
Otherwise, the MULT s-expr is eval-
uated (note that the T forces this s-expr
to be evaluated if the first test fails).
The MULT contains a recursive call on
FACTORIAL; the argument passed to
FACTOIUAL here is N-1. The value
returned by this call is multiplied by
the "current" value of N [remember
that each time FACTORIAL is invoked,
a new "local" N is created and bound
to the actual argument).

A handy way to observe the evalua-
tion of a function is via a function
trace. Most decent LISPs are supplied
with some mechanism for tracing func-
tions, an indispensable debugging aid.
A trace of a function displays the
arguments passed to the function when
it is invoked and the value returned by
the function when it is exited. For ex-
ample, in P-LISP, if you are tracing the
ADD function and type (ADD 4 5), you
would see

> > ADD:: (4 5)

< < ADD:: 9

The > > arrow indicates a func-
tion entering and the < < arrow

indicates a function exiting.

Suppose you want to see how the
evaluation of FACTORIAL proceeds. If
you trace the function and type (FAC-
TORIAL 4), you will see the following:

>> FACTORIAL:: [4)

(level 1 — value of N is 4)
>> FACTORLfUL:: (3)

[level 2 — value of N is 3)
> > FACTORL\L:: (2)

(level 3 — value of N is 2)
> > FACTORL^;: (1)

(level 4 — value of N is 1)
> > FACTORL\L:: (0)

(level 5 — value of N is 0)
<< FACTORIAL:: 1

[level 5 — 1 is returned)
<< FACTORIAL:: 1

(level 4 — 1 is returned)
< < FACTORIAL:: 2

[level 3 — 2 is returned)
<< FACTORL\L:: 6

[level 2 — 6 is returned)
<< FACTORIAL:: 24

(level 1 — 24 is returned)

Note that each level has its own
"local" N, and the value of this N is
multiplied by the value returned by
FACTORIAL from the next level down.
Although recursion is usually a sim-
ple and elegant way to solve a program-
ming problem, it is not always the best
method to use. In particular, recursion
tends to be inefficient. A great deal of
overhead is involved when entering a
function and setting up the local en-
vironment, both in execution speed
and memory consumption. If these fac-
tors are critical, such overhead should
be kept to a minimum. Luckily, LISP is
provided with an iterative program-
ming capability called PROG. Here is
the definition of FACTORIAL using a
PROG instead of recursion:

(FACTORIAL (LAMBDA (N)
(PROG (PROD)
(SETQ PROD 1)
LOOP
(COND
( (EQUAL N 0) (RETURN PROD) )

)

(SETQ PROD (MULT PROD N) )

(SETQN (SUBN 1))

(GO LOOP)

The first part of PROG is a list of
local atoms to the PROG. In the exam-
ple above, PROD is declared a local
atom. Local atoms exist only in the
context of the PROG and disappear
when the PROG is exited. When the
PROG is entered, their values are
intially SETQed to NIL.

Each s-expr in a PROG is evaluated
in succession unless the s-expr is an
atom. Such atoms are considered labels
and are not evaluated (i.e., they are
skipped). In the previous example, the
atom LOOP is a label. The GO function
causes flow-of-control to proceed to the
label indicated in the GO (not unlike a
GOTO in BASIC).

The RETURN function is used to
exit a PROG. The argument of the
RETURN is evaluated and returned as
the value of the PROG. If RETURN is
not used to exit the PROG, then PROG
returns NIL.

The example given for FACTORIAL
should now be easy to understand.
When the PROG is entered, PROD is
SETQed to 1 and the main loop is then
entered. The first part of the loop is a
test. If N is 0, the PROG is exited and
PROD is returned; otherwise PROD is
multiplied by N and N is decremented

MICRO

No. 57 - February 1983

LANGUAGES

(SUB is the subtract function). GO
then brings you back to the beginning
of the loop. As you can see, the
iterative FACTORIAL is functionally
equivalent to the recursive version.
The major difference is that although
the iterative function is longer, it is
probably faster and more efficient than
the recursive one.

LISP functions that are built into
the interpreter are called SUBRs, for
SUBRoutine. Functions that are defined
by the user are called EXPRs. The
EXPRs that you have examined so far
are functions that take a known num-
ber of arguments, as indicated by the
function's formal argument list.

The LISP mechanism for defining a
function for which the number of
arguments is not known is the FEXPR.
FEXPRs are defined using the following
format:

(DEFINE (function-name (FLAMBDA
(formal-argument)

function-body
)))

The difference between a FEXPR and an
EXPR is that a FEXPR contains a single
formal argument in the formal argu-
ment list. When such a function is in-
voked, the formal argument is bound to
the entire unevaluated list of actual
arguments. For example, define the
following function:

(DEFINE (PRINTME (FLAMBDA (X)
X)))

If you now type (PRINTME LISP
LISPER LISPEST), you get (LISP
LISPER LISPEST). The formal argu-
ment X gets bound to the list of actual
arguments (LISP LISPER LISPEST).
Note these arguments are not
evaluated. The function then just
returns X.

If you want to define a function that
adds up an arbitrary number of numeric
atoms, the following functions will
serve your needs:

(DEFINE (ADDLIST (FLAMBDA (X)
(ADDLIST2X))))

(DEFINE (ADDLIST2 (LAMBDA (X)
(COND

((NLILLX)O)

(T (ADD (CAR X) (ADDL1ST2 (CDR X) ) )
))))

Since the function can take any num-
ber of arguments, it has to be declared a

FEXPR. This function, ADDLIST,
simply passes the argument list to the
function ADDLIST2, which recursively
adds up the elements of the list. Note
that a FEXPR should never be recur-
sive, since its arguments are never
evaluated.

The final LISP feature discussed in
this article is the property list, or p-list.
A p-list is a list of properties and prop-
erty values that may be associated with
a literal atom. A p-list has the form

(prop1 value 1 prop2 value2 ...
propn valuen)

For example, you may want to assign
the property COLOR to the atom BALL
with the property value RED. The LISP
function PUT is used to put properties
and values on an atom's p-list. Proper-
ties must be literal atoms; a property
value may be any s-expr. The s-expr
(PUT 'BALL 'COLOR 'RED) puts the
property COLOR with value RED on
the p-list for BALL.

The LISP function GET is used to
retrieve property values. If you type
(GET 'BALL 'COLOR), you will get
RED as the result. GET returns NIL if
the atom does not have the indicated
property on its property list.

Earlier I mentioned that the LISP
function CDR took a list as its argu-
ment. CDR also can take an atom. The
CDR of a literal atom is its property
list. If you type (CDR 'BALL), you'll
get (COLOR RED). The function REM
removes properties from a p-list. Thus
(REM 'BALL 'COLOR] removes the
property COLOR from BALL'S p-list.

What are p-lists good for? Suppose
you want to create a dictionary of
English words to be used by a natural
language processor. The various proper-
ties associated with a word, such as
part of speech, plural form, etc., could
be conveniently stored on a p-list. For
example, the p-list for the atom APPLE
could look like (NOUN T PLURAL
APPLES OBJECT FRUIT SHAPE
ROUND). These properties could be used
by the natural language parser to deter-
mine if a statement was syntactically
correct and semantically meaningful.

P-lists also are used to store func-
tion definitions. LISP determines
whether or not an atom is a function by
checking the atom's p-list for the EXPR
or SUBR property. If the function is an
EXPR, the property value is the func-
tion definition; if it's a SUBR, the prop-
erty value is implementation-
dependent (usually the address of the

interpreter subroutine that evaluates
the SUBR). One way to have a LISP
function create other functions on the
fly is by PUTting the function defini-
tions on atom p-lists.

There is still a great deal about LISP
and its applications that are beyond the
scope of an introductory article. Hope-
fully, your curiosity is piqued enough
to want to learn more about this unique
and fascinating programming language.
The P-LISP package, published by
Gnosis, Inc., is a worthwhile invest-
ment for those who own an Apple and
want to become part of the world
of LISP.

References

1. Allen, John, Anatomy of LISP,
McGraw-Hill, 1978.

2. Bagley, Steven and Shrager, Jeff, The
P-LISP Tutorial, Gnosis, Inc., Phila-
delphia, PA, 1982.

3. Horn, B. and Winston, Patrick,
LISP, Addison-Wesley, 1981.

4. Siklossy, L., Let's Talk LISP,
Prentice-Hall, 1976.

5. Winston, Patrick, Artificial Intelli-
gence, Addison-Wesley, 1977.

You may contact the author at 1041 Penn
Circle F-606, King of Prussia, PA 19406.

JMCRO

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No. 57 - February 1983

MICRO

AMOK)

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MICRO

No. 57 - February 1983

/MOK)

PET Vet

By Loren Wright

Sound on the Commodore 64

My December column (MICRO 55:54|
covered the exciting graphics features
of the Commodore 64, including sprites
and high-resolution graphics. The
Commodore 64 's sound includes many
capabilities found only on dedicated
synthesizers. In this column I explore
the C64's sound features and then
review some sound software.

The Problems

The sound capabilities of most com-
puters, and even most add-on boards,
are limited. Sounds programmed with
these usually don't come close to their
natural counterparts. It's not sur-
prising, considering the way most com-
puter sound is produced.

According to the theories of a
physicist named Fourier, all sounds can
be constructed by combining sine
waves (figure 1) of the right frequen-
cies. Full-fledged synthesizers allow
full control over how much of each sine
wave is used. In addition, the phase of
each can be varied. As a result, synthe-
sizers can duplicate nearly any sound.

How is music usually produced
with home computers? On the PET and
many others it is possible to set up a
square wave on the CB2 line of a 6522
(VIA) by using an internal timer and the
serial shift register. A square wave
sounds a bit like a clarinet. The VIC
and Atari computers use more sophisti-
cated systems, with special chips par-
tially dedicated to music.

Musical sounds are usually com-
posed of a single, fundamental fre-
quency that determines the pitch of the
note, and various amounts of the har-
monics, or multiples, of the funda-
mental frequency. For instance, a
triangle wave consists only of odd har-
monics, each in a proportion deter-
mined by the reciprocal of the square of
its harmonic number. Therefore, a

triangle wave is dominated by the
fundamental, with the third harmonic
only 1/9 as loud, the fifth only 1/25 as
loud, and the other odd harmonics
much softer. It is difficult to produce a
sine wave with inexpensive digital cir-
cuitry. The more attainable triangle
waveform looks and sounds similar to
the sine wave, and although you can
certainly hear the difference, it is a
satisfactory replacement.

The Commodore 64 has three
voices, each of which can be pro-
grammed with a triangle, rectangular,
sawtooth, or random noise waveform,
shown in figure 2. The rectangular
wave's pulse width is programmable.
The 6581 (or SID) chip has a great
number of other capabilities, including
filtration, synchronization, and ring
modulation, which I'll discuss later.

The Envelope Please

Natural sounds seldom start im-
mediately with their full volume, nor
do they end abruptly. Think of the
way they are produced. With a piano, a
little hammer hits a string; with a
violin, the hairs of the bow catch the
string; with a wind instrument, the im-
pact of the player's tongue starts the
sound. How can a computer simulate

Figure 1: Sine Wave

the natural variations of volume within
a single note?

Most computers don't. The Com-
modore 64 and real synthesizers use
what is called an envelope for each note
(see figure 3). There are four com-
ponents of the envelope: attack, decay,
sustain, and release. Attack is the time
it takes for the note to increase from no
volume to its maximum volume.
Decay is the time it takes the volume
to decrease to the sustain level, which
is maintained for most of the duration
of the note. Finally, release is the time
it takes to go from the sustain volume
level to silence again.

The shape of the envelope can be
programmed. The durations of the at-
tack, decay, and release portions can
each be programmed to sixteen dif-
ferent values. The volume level of the
sustain portion can be set to sixteen dif-
ferent proportions of the peak volume.
There is a gate bit for each voice. When
this bit is set to 1 the attack begins,
followed by the decay and the sustain,
where it stays until the gate bit is reset
to 0. Then the release portion of the
envelope begins.

This information is all you really
need to know to use the 64 for simple
music programming. Just select the fre-
quency (this requires two POKEs), the
waveform, the envelope parameters,
and the overall volume. Then set the
gate bit, leave it set for the length of the
note, and reset the bit when the note is
done. Multiple voice music is a matter
of doing things in the right order and at
the right times. Actual programming is
a bit more complicated since individual
bits must be changed without disturb-
ing the others.

Filters

An audio filter functions in a way
analogous to a paper coffee filter. The
paper filter has little holes that will let
the coffee pass through, but not the
grounds. Make the holes a little bigger,
and some of the finer grounds will pass
through. The audio filter acts on fre-
quencies and there are two basic kinds

No. 57 - February 1983

MICRO

of filters: low-pass and bigb-pass. A
low-pass filter allows low-frequency
waves to pass through, while the higher-
frequency waves are blocked to a con-
siderable extent. A high-pass filter re-
jects low-frequency waves and allows
high-frequency waves to pass. The
borderline is called the cutoff fie-
quency. The C64's SID chip allows ap-
plication of bigb-pass, low-pass, band-
pass (rejects high and low), or any com-
bination of the three. The cutoff fre-
quency and resonance, or sharpness, of
the filter can be selected. However,
there is only one filter unit, which can
be switched in or out for each voice, so
you can't filter the voices differently.

If you set the cutoff frequency
somewhere above the fundamental fre-
quency and apply the filter in the low-
pass mode, you will get a purer sound-
ing, though softer, tone. The filter can
also be applied in the high-pass mode to
increase the harmonics, while atten-
uating (i.e., reducing the volume) of
the fundamental.

Synchtonization and
Ring Modulation

These sophisticated controls can be
used to produce complex waveforms.
Syncbionizatioii causes the voice to
lock onto thf frequency of another
voice. Voice 1 syncs with voice 3, voice
2 with voice ' , and voice 3 with voice
2. Dependin.^: on the two frequencies,
interesting effects can be produced.

Ring modulation is the result of ad-
ding and subtracting two waveforms.
When ring modulation is on for a par-
ticular voice, its output is the result of
modulating from another oscillator.
Non-harmonic frequencies (i.e., not
multiples of the fundamental fre-
quency) result, and very strange sovmds
can be produced. As its name implies,
this can also be used to produce bell or
chime effects. Voice 1 is modulated by
voice 3, voice 2 by voice 1, and voice 3
by voice 1.

Voice 3 has extra controls available.
Its output can be turned off — useful for
synchronization and ring modulation
used on voice 1 when you don't want to
hear the driving frequency. In addition,
the oscillator and envelope generator
outputs are available in digital form in
two SID registers. When random noise
is selected as the waveform for voice 3,
the oscillator output is a very good
source of random numbers.

The sound output is available in a
form compatible with good sound

systems, so you don't have to rely on
your TV's poorer system.

Ptogtamming C64's Sound

It is difficult for the BASIC pro-
grammer to take full advantage of all
the SID's capabilities. Even such sim-
ple things as setting the gate bits re-
quire ANDing and ORing. Machine
language is more effective when some
of the more sophisticated features are
involved.

In MICRO'S Commodore 64 Data
Sheet (MICRO 55:109) most of the
SID's registers were inadvertently
omitted. See page 9 in this issue for a
complete list.

The Commodoie 64 User's Guide
and the Piogiammei's Reference Guide
include a number of sample programs
that demonstrate most of the C64's
music capabilities. The software
developer's kit I mentioned last month

F/0ure 2a: Triangle Wave

includes a SID monitor and a fancy
music program. The monitor allows
you to change the contents of just
about every SID register, while you
listen to the result. The music program
has a number of pre-programmed
pieces, from "Magic Trumpet" to a
Bach chorale. You can select an "in-
strument" for each voice, the tempo,
and a few other parameters. As the
music plays, the tune is displayed as
notes on a clef. The part of the program
that lets you compose your own music
is not very good. The notes are keyed in
by their alphabetic representations.
This might be OK for copying sheet
music, but it's not very good for the
trial-and-error composing most of us
are likely to do. Abacus Software's
"Synthy-64," reviewed below, makes
programming of multi-voice music a
lot easier.

A third type of music program is in-

Flgure 2b: Sawtooth Wave

r\ f]

Figure 2c: Pulsed (rectangular) Wave

Figure 2d: Noise Waveform

MICRO

No. 57 - February 1983

teractive — one that allows you to play
music in real time. The "Piano Key-
board" program in the user's manual is
an example. It is impressive for what it
does, but its limitations soon become
apparent. Only one note can be played
at a time. That's because the GET func-
tion can only read one key at a time.
Also, it's easy to get ahead of the
BASIC program. The effect is flattering
for someone with uncoordinated
fingers — the notes come out evenly
spaced — but for others it is frustrating.
A more complete interactive music
program requires machine language for
speed and should read the keyboard
matrix to detect more than one key
down at a time. Throw in a real
musical keyboard, perhaps interfaced
through the controller and parallel
ports, and you would have something
resembling a real synthesizer. Consider
it a challenge!

Synthy-64:

A Music Composition Program

Abacus Software's "Synthy-64" by
Roy Wainwright is a music composi-
tion program that is considerably easier
to use than the Commodore program
described above, and a lot easier than
figuring out all the POKEs yourself.
Users familiar with musical notation
will find Synthy-64's notation easy to
grasp. Notes are entered with their
alphabetic representations, followed by
the octave number, a slash, and a
number indicating the length (I for
whole, 2 for half, etc.). Octave
numbers and durations remain the
same, until changed, so shorthand
notations can be used. Flats, sharps,
naturals, key signatures, dotted notes,
double-dotted notes, triplets, repeats,
and rests are all easy to use. A sample
program line is shown below.

10 SGN%2 B5/8 C/16 D E F G A6 B/2

Tempo and volume can be changed
at any point during the composition.
You can also program a "portamento"
as if it were a regular musical note. A
portamento is a continuous sweep, up
or down, in the pitch of a note. The rate
of sweep can be selected with a
multiplier parameter.

The three voices are indicated with
+ , - , and £ prefixes. As with octaves
and note durations, these designations
are inherited by the next note, unless
otherwise changed. The Synthy-64 in-
terpreter has a read ahead feature that

Figure 3: Envelope

SUSTAIN

TIME

makes it easy to keep the three voices
synchronized. There is no way to in-
dicate measvires, but this can be done
by adopting the convention of using
separate lines for each measuie.

That's all you really need to do
some impressive three-part composing.
The attack, decay, sustain, release,
waveform, filters, etc., are set up with
default values that produce a piano-like
sound. In addition, the skeleton pro-
gram includes convenient subroutines
for flute, trumpet, banjo, accordian,
and piano sounds. All of these registers,
as well as ring modulation and synchro-
nization, can be controlled with simple
commands to set up your own sounds.

Synthy-64 is an interpreter that
replaces the C64's BASIC interpreter,
so most BASIC keywords don't work or
work differently. The rudiments are
there for control of program flow:
GOTO, GOSUB, RETURN, STOP,
END. The INPUT command is
modified to handle multiple choice
menus like a BASIC ON... GOTO.
Text, including all C64 control and
graphics characters, can be displayed
simply by enclosing the characters in
quotes. Just about everything else is
missing, including the POKE state-
ment needed to change screen or border
colors jit works in immediate mode,
but not within a program). LOAD and
SAVE operations are implemented for
both cassette and disk.

I found only two minor bugs in
Synthy-64. The manual says you can
tie a portamento to the previous note.
My attempts to do this resulted in the
interpreter skipping the portamento.
Also described is a "skip ending"
feature to repeat a phrase, skipping the
rest of the program line, until a

specified number of repeats have occur-
red. Instead, the remainder of the line
is played the specified number of
repeats, and then it is skipped —
backwards! Synthy-64 changes octave
designations between G and A, rather
than the more conventional C split.

The manual is an adequate refer-
ence, although there are numerous
typographical errors, a few of which
result in misinformation.

Synthy-64 is, in general, a well-
done, convenient music composition
program. Nearly all of the C64's power-
ful sound features can be exploited.
It is available for $35 from Abacus
Software, P.O. Box 7211, Grand
Rapids, MI 49510.

MICRO'S VIC BOOK
Available in March

I am currently editing, writing, and
programming for MICRO'S VIC book,
to be released in March. Unlike most of
MICRO'S articles, the content will be
aimed at the newcomer — the person
who is just beginning to realize there is
more to computing than running canned
software. Eight or more useful and
entertaining programs will be included
on cassette and listed in the book, as
well. The text that accompanies each
program will aim first at using the pro-
gram, then at making improvements by
changing lines, and finally at
understanding how the program works.

The most exciting program is one I
call "MICRO Calc." MICRO Calc
allows you to define elaborate mathe-
matical calculations, make convenient
changes, and calculate the results at the
touch of a key. Screens can be saved on
tape for future use. In addition the pro-
gram can be used to learn how BASIC
expressions work.

JMCRO

No. 57 - February 1983

MICRO

68000 Program Control:
Branch and Jump Instructions

by Joe Hootman

The 68000 installment this
month covers the branch and
jump Instructions, both
conditional and unconditional.

Branch and jump instructions allow the
transfer of program control to another
portion of the program. There are two
basic types of program control instruc-
tions: the unconditional jump/branch
and the conditional' jump/branch.
Table 1 catalogues the unconditional
program control statements, and table
2 contains the conditional program
control statements.

There are three basic types of uncon-
ditional program control instructions
(table 1). The first type is the branch
always (BRA) and jump (JMP). The
BRA instruction branches with either
an 8-bit or 16-bit displacement from
the existing program counter contents.
The JMP instruction jumps to an effec-
tive address expressed in the opword.

The BRA and JMP instructions do
not save any return address informa-
tion. If you want to return to the in-
struction following an unconditional
branch, then you must Branch to Sub-
routine (BSR) or Jump to Subroutine
(JSRj. Both the BSR and JSR store the
next instruction address on the stack
before the next instruction is executed.
The BSR instruction uses a specified
displacement to designate the next in-
struction and the JSR instruction
calculates an effective address to locate
the next instruction to be executed.

The last type of unconditional
branch is the Return and Restore CCR
[RTR] and Return from Subroutine
(RTS]. These instructions are used at
the end of a subroutine to return pro-
gram control to the main program. A
return is used when you want to con-
tinue execution at the original program
location. When RTR is used, both the
program counter and the CCR are

Table 1: Program Control Branch and Jump Instructions

Mnemonic Dau Size/CCR Name Comments

BRA

8, 16

(offset

displacement!

CCR

XNZVC

Branch
Always

The program will always continue executing at
the PC + displacement. The displacement is
either 8 or 16 bits and is in two's complement
form, the displacement is measured in the
number of bytes.

Opworc

15 14 13 12 11 10 9 8

Format

7 6 5 4 3 2 10

110

8-bit displacement

16-bit displacement

The 16-bit displacement is zero if the 8-bit
displacement is used.

BSR

8, 16

Branch to

(offset

Subroutine

displacement)

CCR

XNZVC

The address of the instruction immediately
following BSR is stored on the system stack.
The PC is loaded with PC + displacement.
The offset displacement is either an 8-bit or
16-bit displacement and is expressed in two's
complement form

Opword Format
15 14 13 12 11 10 987654321

1 10 1

8-bit displacement

16-bit displacement

If the 8-bit displacement is zero, the 16-bit
displacement must be used. Note a zero
displacement cannot be used.

IMP

CCR

XNZVC

Jump

The program will continue to execute at the
address specified by the instruction. The address
is specified by the addressing modes.

Opword Format

15 14 13 12 11 10 9 8765432 10

10 1110 11

Effective Address
Mode I Register

The effective address specifies the address of the
next instruction. The following address modes
cannot be used: 1, 2, 4, 5, 12, 13, 14.*

JSR

Jump to The address of the instruction immediately

Subroutine following the JSR instruction is pushed onto
the system stack and the program continues
execution at the address specified.

Opword Format

15 14 13 12 1110 9 8 76543210

CCR
XNZVC

10 1 1 10 10

Effective Address
Mode I Register

The effective address mode specifies the location
of the next location. The following address
modes caimot be used: 1, 2, 4, 5, 12, 13, 14.*

(continued)

MICRO

No. 57 - February 1983

Table 1 (continued)
Mnemonic Data Size/CCR Name

Comments

RTR

CCR

XNZ VC
pulled fiom
stack

Return and The PC and CCR are pulled from the stack and

Restore restored.

Condition

Codes Opword Format

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1

010011100 1110111

RTS

CCR
XNZ VC

Return from The PC is puUed from the stack and the previous
Subroutine value of the PC is lost.

Opword Format

IS 14 13 12 11 10 9 8 7 6 5 4 3 2 1

10 1110 1110 10 1

TAS

CCR

XNZVC
-..00

Test and
Set an
Operand

The TAS instruction sets N if the most
significant bit of the data is set, and cleans N
otherwise. The Z bit is set if the data is zero.

Opword Format

IS 14 13 12 11 10 9 8 7 6

5 4 3 2 10

10 10 10 11

Effective Address
Mode 1 Register

The following address modes cannot be used: 2,
10, 11, 12, 13,14.'

•Addressing modes will be covered in future issues.

Table 2: Program Control Instruction (with tests)

Mnemonic Data Size/CCR Name Comments

BCC

8, 16

(offset

displacement]

CCR

XNZVC

Branch
Condition-
ally

If the specified conditions of the CC table
are met, the PC will be loaded with the PC +
[offset) and the execution of the program
continued. The offset is specified in two's
complement form, either 8 or 16 bits.
Opword Format

15 14 13 12 11 10 9 8

7 6 5 4 3 2 10

110

Condition

8-bit displacement

16-bit displacement

The 8-bit displacement is the two's complement
specifying the relative distance between the
branch and the instruction that is to be branched
to. If the 8-bit displacement is zero, the 16rbit
displacement is used.

DBCC

Test

(offset

Condition

displacement!

Decrement

CCR

and

XNZVC

Branch

If the specified condition of the CC table for
the loop is not true, the low order 16 bits
of the counter data register are decremented
by one. If the result is - 1, the execution
continues with the next instruction. If the result
is not — 1, execution continues at the current PC
+ the sign extended 16-bit offset displacement.
The PC is the current instruction plus 2.

Opword Format

15 14 13 111110 9 8 7 6 5 4 3 110

10 1

Condition

1 1 1

displacement

The condition field is specified by the 16 bits in

the CC Uble.

The register field specifies the data register

which is the counter.

The displacement field specifies the distance of

the branch.

(continued)

pulled from the stack. When RTS is
used, only the progam counter is pulled
from the stack.

The Test and Set an Operand (TAS)
is designed to control the access of the
68000 to shared RAM. The TAS in-
struction is a read/modify/write in-
struction and tests the data to see if the
most significant bit is set. The byte of
data is returned to memory with the
most significant bit set. The TAS is
designed to allocate RAM to multiple
users. If one of the multiple users
wants to use a portion of RAM, he first
reads the "TAS bit." If the most
significant bit is set, the user knows
that memory immediately adjacent to
the TAS is being used. If a TAS byte has
a zero in the most significant bit posi-
tion, the user knows memory is avail-
able for use. The most significant bit is
then set on the TAS byte and returned
to memory to indicate that the memory
immediately adjacent to that TAS is be-
ing used.

The conditional transfer of control
from one part of a program to another is
accomplished by testing one or more of
the bits in the CCR. The conditional
branches are given in table 2. The
branch conditional instruction tests
the bits in the CCR in accord with the
CC table and branches if the conditions
are met. The branch displacement is
expressed as a two's complement 8-bit
or 16-bit offset. If the 8-bit displace-
ment is zero, the 16-bit displacement is
used; if the 16-bit displacement is zero,
the 8-bit displacement is used.

The Test Condition Decrement and
Branch (DBCC) instruction is useful
because it will count the number of
times a specified condition in the CCR
is not true. One of the data registers is
used as a counter, and when the value
in that register reaches - 1, the instruc-
tion immediately following the DBCC
instruction is executed. DBCC is
useful for implementing a loop while a
condition is true in the CCR.

The Set According to Conditions
(SCC) is an instruction that tests the
particular bits in CCR and sets the byte
specified by the EA. If the condition is
not true, the byte is set to zero.

No. 57 - February 1983

MICRO

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Chi-Square, Fisher Exact, Signed Ranks

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Table 2 (continued)

Mnemonic Data Size/CCR

Name

Comments

sec 8

Set

The specified condition of the CC table is tested.

CCR

According

[f the specified condition is true, the byte

XNZVC

specified by the £A is set to all ones,

Condition

otherwise the byte is set to all zeros.

Opword Format

15 14 13 12 11 10 9 8 7 6 5 4 3 2 1

10 1 Condition

1 1

Effective Address

Mode 1 Register

The condition field is specified by one of the 16

codes given by the CC table.

The effective address field specifies the location

of the T/F byte. The following address modes

cannot be used: 2, 10, 11, 12, 13, 14.*

CC Table

Name

Code

CCR Tested

Name Code CCR Tested

CC Cairy Clear

0100

LS Low or same 0011 C + Z

CS Carry Set

0101

•LT Less than 1101 NV + NV

EQ Equal

0111

MI Minus 1011 N

•GE Greater or equal

1100

N-V + N-V

NE Not equal 0110 Z

•GT Greater

1110

NVZ + NVZ PL Plus 1010 N 1

HI High

0010

•VC Overflow clear 1000 V

•LE Less or equal

Z + N-V + NV

•VS Overflow set 1001 V

••F False

0001

••T True 0000 1

* Conditions used with two's complement arithmetic.

* * These tests are used for SCC, DBCC only.

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No. 57 - February 1983

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More on Tiny PILOT
for the PET

by Arthur Hunkins

The author's observations
include how to solve a few tricky
problems, more detailed
explanations of some
commands, and how to convert
the program for 8K PET.

As an educator, I appreciate PILOT as a
simple, instructionally oriented, first
language. Therefore, I was fascinated
by the article, "Tiny PILOT for the
PET" (MICRO 49:73), by Jim Strasma
and John O'Hare. Since this PILOT re-
quired only 2K of memory, I couldn't
wait to code it into my Upgrade 8K PET.

I quickly discovered, however, that
Strasma and O'Hare's code was for 32K
PET/CBM. Many changes are required
to convert it to 8K. The modification,
though time-consuming, is straight-
forward and easy to explain. It involves
changing all numbers in the range
$78-$7F to the range $18-$1F, and
beginning the code at $1800. Excep-
tions to the number changes are these:
do not change a number in the range of
$78-$7F if it is followed immediately
by a second number in the same range
— change only the second number. For
an example see the Tiny PILOT listing
(MICRO 49:75]: leave the value in
$7846 as is and change the one in
$7847. Also, three other locations
should not be changed: $78AD, $7838,
and $7F2E. That's it for the coding
changes.

The initialization sequence for the
8K version becomes NEW:SYS7936
($1F00 instead of $7F00J. To run
PILOT programs, do SYS6145, or use
the ordinary RUN command.

This relocated Tiny PILOT runs on
any PET/CBM with Upgrade ROMs
and 8K or more of memory. The 6K not
used by PILOT should be adequate for
most PILOT programs. For the excep-
tional case, the conversion instructions

above permit tailoring Tiny PILOT to
any size memory on a 4K boundary. For
example: on a 16K PET, convert
$78-$7F to $38-$3F (with the excep-
tions mentioned), start coding at
$3800, and initialize at $3F00.

The initialization routine protects
PILOT one page lower than necessary
in high memory, reserving 2.25K in-
stead of 2K. If you need the additional
page, change $7F10 and $7F11 (or
$1F10 and $1F11 in the 8K adaptation)
to $EA (NOP). You may alternately
POKE7952,234 and POKE7953,234 in
the 8K version or, after initializing,
simply POKE53,24.

To understand Tiny PILOT better,
the reader should consult the article
containing the original Tiny PILOT,
upon which Strasma and O'Hare based
their version for the PET. "Tiny
PILOT: An Educational Language for
the 6502," by Nicholas Vrtis (MICRO
16:41), offers substantial and lucid
details of user operation and internal
programming logic.

One of the attractive features in the
new implementation is the incorpora-
tion of graphics and cursor control
features into the screen display,- e.g.,
RVS field, CLR screen, and placement
of text or graphics anywhere on the
screen. In addition, there are special
statements that reverse the field of
everything currently displayed, and
that scroll the screen up or down. The
statements D: (Delay) and W: (Wait)
also are particularly relevant to the in-
structional environment. Such educa-
tionally meaningful features in a 2K
package are unique indeed.' Tiny
PILOT'S statements are both highly
practical and readily comprehended by
the young computerist.

There are other user-oriented
features. Hitting RETURN in response
to I:, ?:, or A: statements gives either

zero or a null string; it does not knock
you out of the program as does BASIC'S
INPUT (press STOP to exit the pro-
gram). Also, L:G-Z, unimplemented
subroutines that might inadvertently
find their way into a program, return
appropriate ERROR messages — they
do not bomb leaving the user buried in
a machine-language crash.

Special challenges occur when you
attempt to deal with string variables in
Tiny PILOT. The language's greatest
limitation — and the one that saves the
most memory — is a near lack of string
variable capability. (Some modest addi-
tional capacity in this area would be
most welcome.) As it stands, the only
viable string variable applications
involve matching responses, and incor-
porating the user name string and
strings converted from numerics in
text. The only directly specified string,
the name string $?, is entered by the
user in response to a ?: statement. It is
later referenced in Match and Type
statements.

Numerics may be included in text
only by first converting them into
strings. This is accomplished with the
Compute statement, C:$ = N, where N
is a previously defined numeric vari-
able (see Sample Program, MICRO
49:74). The same conversion is re-
quired for Match, as matching is done
only on text strings. Thus, 20, 2/5 and
"2gether" all match with 2. This
feature is awkward when the intent is
to match numbers. One solution, again
illustrated in the Sample Program is to
subtract the numbers from one another,
convert the result to a string, then
Match to zero. In PILOT code these are:
C:R = A-B, C:$ = R, M:0, where A and
B are the numbers being compared.

There are two important omissions
in the list of PET Tiny PILOT Program
Statements (MICRO 49:73). E:, listed

MICRO

No. 57 - February 1983

in the original Vrtis article but absent
here, is an Exit from Subroutine used in
conjunction with U: (Use Subroutine).
The combination of U: and E: gives
PILOT a highly viable subroutine
capability. (By the way, E:, in contrast
to BASIC'S RETURN, is simply ignored
when not executing a subroutine — a
useful feature in some situations.)

The other error is in the fourth Pro-
gram Statement: TEXT should read
M:TEXT. This line describes the
Match statement (also clarified by
Vrtis). Note that, as mentioned above.
Match operates only on text, and that
multiple Matches are allowed per state-
ment (commas separating the Match
items). The Match option M: - checks
for a negative "number" — evidently a
minus sign as the first character. M: -i-
is not implemented, but would be a wel-
come and memory-efficient addition.

You should be aware of several little
quirks in the operation of Jump and Use
Subroutine statements. With J:A (Jump
to last Accept), you get an ERROR
message if you attempt to jump back
out of a subroutine you previously

jumped into. J:A works fine as long as it
is not inside a subroutine. Also be sure
to reserve J: A for jumping to the last en-
countered A: (Accept) statement. "A"
is a reserved label and any use of "A"
as an ordinary label will result in an ER-
ROR message. The referenced A: state-
ment must already have been en-
countered in the program,- jumping
ahead to A: is not possible. Note, too,
that U:A (Use Subroutine starting at
last Accept) is not dependable. Such a
branch can be accomplished by giving
the Accept statement a regular label
(such as *ZA:), and referencing it (U:Z).
I would like to suggest two addi-
tional enhancements to Tiny PILOT.
First, since the P: statement generates
only random integers from 1-99, get-
ting random numbers in any other
range is cumbersome (though possible).
An optional extension to the routine,
specifying a different range (for exam-
ple, P:X,7 for a 1-7 span), would
simplify coding. Second, a numerical
Match statement (with positive and
negative compare) also would help
compact code.

In any case, if you have a PET/CBM
with Upgrade ROMs, try Tiny PILOT.
It's a most worthwhile educational in-
vestment, especially for the young com-
puterist just beginning to program. And
it won't cost you anything but time.

Editoi's Note: "Tiny Pilot for PET"
was published as object code only.
Those wishing to have this program for
4.0 BASIC may want to obtain the
source code from:

ASM/TED Users' Group

c/o Brent Anderson

200 S. Century St.

Rantoul, IL 61866

Arthur B. Hunkins may be contacted at
the School of Music, UNC-G, Greensboro,
NC 27412.

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MICRO

No. 57 - February 1983

A BASIC Match Routine

for CAI

by Robert Phillips

Using a match routine, CAI
authors can effectively trap
errors, isolate mistakes, and
overlook typographical errors.
This article discusses some
uses for a match routine, and
presents such a routine in
BASIC.

MATCH

requires:

A Microsoft BASIC

One of the nice things about a com-
puter is its unfailing accuracy; yet one
of the frustrating things about a com-
puter is that same compulsive accuracy
— it can't even recognize a simple
typographical error. But users in-
evitably make typographical errors;
also, they may make responses to ques-
tions in a program that the author
didn't anticipate, such as "sure" in-
stead of "yes." The programmer must
try to overcome these problems. When
he asks a "yes/no" question, for exam-
ple, he may test the first letter of the
response and if it is a 'Y' he can assume
the answer is affirmative. He can use a
statement such as

IF LEFT$(A$,1) = 'Y' THEN GOTO 999

and have the program branch ap-
propriately, regardless of the answer
(YES, Y, YEP, YEAH, etc.). However,
when designing teaching materials for
CAI (Computer- Assisted Instruction),
the programmer may find himself fac-
ing difficulties because of typographical
errors and misspellings. He must find a
way to determine if the response
matches what he is looking for. The
purpose of this article is to show some
ways in which a "match" routine can
be used to write CAI effectively, and to
present my MATCH algorithm, writ-
ten in Applesoft and adaptable to most
dialects of BASIC).

The Match Routine

Originally I wrote this algorithm in
PL/ 1 for use on an IBM 360. Since I
knew it worked there, I translated it
from PL/1 into BASIC, rather than
starting from scratch in BASIC. Some
of the logic shows its PL/ 1 parentage. I
followed IBM's method of using the
match facility ("Partial Answer Pro-
cessing") in their CAI language
Coursewriter (the " • " will not match a
blank character).

Since Applesoft BASIC does not
have a built-in index or position func-
tion, I use the MID$ function to scan
the string for the items to be matched.
When an asterisk is found, its position

is noted, and then it is replaced by a
slash (/) in both the author's string and
the student's response. This replace-
ment effectively masks the character to
be ignored by making it identical in
both strings. Note that it is necessary
to find the sections separated by amper-
sands before masking with the aster-
isks; yet, the asterisk means to ignore a
character. This is the most difficult
part of the algorithm. (For a completely
different way of attacking this problem,
see the discussion on a match algo-
rithm in the publication Fiontend from
CONDUIT, University of Iowa.)

Take a closer look at how the rou-
tine works. There are four possibilities:

Listing 1 THE MATCH ROUTINE

100 REM)) MATCH ALGORITHM <(

102 R : 0: IF St = At THEN R < 1 RETURN

104 FOR Zl = 1 TO LEN <At):IF MI D« < At , Z 1 , 1 ) = "S" THEN GOTO 112

lOi NEXT Zl: Z2 : 1: Zl : 0: Zlt < Alt: Z2« :: St: COSUB 1S4

lOB ZS = LEN(Zlt): IF MI Dl ( Z 1 t , 1 , ZS ) > MI Dl ( Z2 I , 1 , ZS ) AND LEN<Z2t) ^ ZS THEN

R = 1
110 RETURN

112 Za =0: IF Zl = 1 THEN At > MIDt(At,2l GOTO 120
114 Z3I > LEFTt (At ,Z1.1 ) : Z4t : LEFTt ( S t , Z 1 - 1 ) : Zlt = Z3I Z2I =: Z4I GOSUB

1S4
lU IF Zlt <) Z2t THEN RETURN
11) At : MIOt (At ,ZU1 ) : St = MIOt(St,ZUl)
120 FOR Zl = 1 TO lEN(At): IF MI Dt ( At , Z 1 , 1 ) = "$" THEN Z3t =

MIDt (At , 1 ,Z1-1) : GOTO 126
122 NEXT Zl: Zl = 0: IF lEN(At) = THEN R = 1 : RETURN
124 Zl > 0: Z3t > At: At :: ""

12i FOR Z4 « 1 TO lEN(Z3t); IF MI Dt ( Z3 t , Z4 , 1 ) • "•" THEN GO TO 138
128 NEXT Z4: Z4 < 0: Z« . Zl - 1 IF Zl > THEN li ^ LENCZJt)

No. 57 - February 1983

MICRO

1. there are no masking characters; 2.
the only masking character is ' • '; 3. the
only masking character is '&.'; or 4.
both '•' and '&' are used as masking
characters. The first two possibilities
(no mask or only asterisk) are easy to
check. First I check (line 102) to see if
A$ and S$ are equal. If they aren't, line
104 looks for the position of the first
ampersand., If none is found, line 106
invokes the asterisk mask subroutine
in line 154. If any asterisks are present,
they are masked there. When the sub-
routine returns to line 108, Zl$ and
Z2$ are the masked versions of A$ and
S$. They are tested for equality,- if they
are equal, R is set to 1 . The match rou-
tine then returns. (You do not need to
set R = 0; you do that when you enter
the match routine, and set R = 1 only
just before a RETURN. That way the
"default" at return is 0.)

Lines 154-166 are the "asterisk sub-
routine," used to mask an asterisk. Z2
is a switch to skip line 156, which
deletes leading blanks,- this is necessary
when ampersands are used also. Line
158 finds the position of the asterisk. If
none is found, the subroutine returns.
Line 162 checks to be sure that it is a
non-blank character. If it is a blank,
you know that the match has failed.
You don't need to return to the match
routine, so POP the calling address in-
side the match routine and RETURN to
where the match routine was invoked.

If the character is not blank, lines
164-166 replace the asterisk with '/'in
A$, put a slash in the same position in
S$, and then go back to line 158 to find
any other asterisks. If not, it RETURNS
to the line that called it. The choice of
the slash as the mask was purely arbi-
trary. I felt that it was unlikely to occur
in things my students write. You can
change it to something else, such as a
control character or a non-printing
character; e.g., CHR$(92), the
backslash.

As I plaimed the match routine, I
realized that the best way for me to pro-
ceed was to compare from the front to
the first ampersand, make a new string
starting after the ampersand, and com-
pare to the next ampersand, etc. If any
section cannot be found, the match has
failed and the routine returns 0.

To make things as clear as possible,
in the following discussion I call each
part a 'segment.' I define segment as
any part of A$ between two amper-
sands, or between the begirming and

Listing 1 fContiaued)

130 Z9 := LEN(Z3$); FOR Z7 = 1 TO LEN(S»)-Z'»1 IF MI D ! ( S , Z7 , Z 9 ) = Z3! THEN

GOTO 134
132 NEXT Z7: RETURN
134 If Z7 ( Z8 THEN RETURN
134 Ze = Z7: GOTO 152

138 Z5« = LEfT$(Z3l,Z4-l) : Z4 = Z4 - 1: Z7 = 1
140 Z? • LEN<Z5$): FOR Z7 . Z7 TO LEN<S1)-Z9: IF Ml D8 ( S I , Z 7 , Z 9 1 « Z5S THEN

GOTO 144
142 NEXT Z7: RETURN
144 IF Z7 ( ZB THEN RETURN
144 Z8 = Z7; Z4 = Zl - 1; Z4» = MI D» ( S $ , Z7 , Z4 ) : Z2 • 0: ZU = Z3S: Z2! =

Z4»: GOSUB 154: IF ZIJ <) Z2« THEN Z7 = Z7 + I GOTO 140
148 25 = LEN(Z1$): IF MI D» ( 2 U , 1 , Z3 ) = MI D$ < Z2 « , 1 , Z5 ) AND LEN(Z2!) < = Z5 +

1 THEN GOTO 132
150 RETURN

132 AS : HIDS(AS ,ZU1 )
154 IF Z2 = THEN GOTO 15S

134 IFLEfT$(ZJ$,l) > " " THEN Z2» - M1DI(Z2I,2) GOTO 154
158 FOR Z3 . 1 TO LENIZIJ): IF MI D$ ( Z 1 $ , Z3 , 1 ) = "•" THEN GOTO 142
140 NEXTZ3: RETURN

142 IF MID$(ZJ»,Z3 , 1 ) « " " THEN POP; RETURN
144 21$ = mD«(Zl$, 1 ,Z3-1 ) + "/" + MID$ (Zl» ,Z3+1 )
144 Z2S s niDS(Z2S , 1 ,Z3-1 ) -f "/" * MI DS < Z2 S , Z3 + 1 ) : GOTO 138

the first ampersand, or between the last
ampersand and the end of the string. If
a segment has one or more asterisks in
it, I call each part separated by the
asterisks a "subsegment." Thus, if
A$ = "& MAN & WOMAN &", there
are two segments ("MAN" and
WOMAN"). It is the same if
A$ = "MAN & WOMAN". If A$ = "&
MAN & WOM»N &" then there are
two segments, with the second con-
sisting of two subsegments. When an
ampersand is detected in A$, the
routine works with these segments,
trying to find each one. Naturally, if at
any time the search for a segment fails,
the routine does a RETURN.

Line 104 finds the location of the
first ampersand and goes to line 112. If
the ampersand is the first character in
the string, there is nothing in front of it
to check, so line 112 strips off the
ampersand and goes to line 120. If the
ampersand is not the first character,
line 114 substrings off the first segment
from both A$ and S$; these segments

are assigned to both Zl$, Z3$ and to
Z2$,7A$, respectively. The routine
then invokes the asterisk function with
GOSUB 154. (Here you want any leading
blanks stripped off, so you must turn
off switch Z2.) After the asterisk mask
has been applied, the substrings Zl$
and Z2$ are compared in line 116. If
they are not equal, the match has failed
and the routine does a RETURN.

If the first segment is successful,
line 118 discards the first segment (and
the ampersand) from A$ and S$. The
program then checks (line 120) for the
position of the next ampersand. If it
finds one, control passes to line 126. If
it doesn't, check the length of A$. If
there's nothing left in it, it means
you've checked the entire response
without doing a RETURN; the match
has been successful, so R = 1 and you
RETURN. If there is still more of A$
left, it means that this is the last seg-
ment and it didn't end in an amper-
sand, so you have to look for an aster-
isk (line 126).

MICRO

No. 57 - February 1983

Listing 2 to invoke and test the match routine

10 HOME: VTAB 1: PRINT TAB (i), "MATCH ROUTINE INPUT ALGORITHM"

PRINT:

PRINT TAB(»)i "(USING BASIC ROUTINE)": VTAB 12

20 PRINT; INPUT "INPUT 'AUTHOR' STRING --> ";A»: IF NOT LEN(A»)

THEN At <

0L»: GOTO 50

30 TEIT: VTAB 8: CALL -»58: PRINT "A» = • " ; A»; : POKE 34,10

HOME

10 0L» = A»: ir A» = "END" THEN TEIT: HOME: VTAB 21: END

30 PRINT: INPUT "'STUDENT' STRING --> "; S«: S« = " " + S« + "

•

60 GOSUBIOO: PRINT: IF NOT R THEN PRINT "NO ";

70 PRINT "MATCH": PRINT: GOTO 20

The coding that starts on line 126
checks any segment that had an amper-
sand in front of it. This means you have
to ignore as much of S$ as necessary to
find the segment specified in A$. Before
you scan for the whole segment, how-
ever, determine if there are any aster-
isks present and, if so, mask them. If
line 126 finds an asterisk, the program
goes to line 138. Here, S$ is scanned
(line 140) for the substring in front of
the asterisk. If it is not found, line 142
does a RETURN with no match. Line
144 checks to make sure that the seg-
ment found is in the string later than
the last segment found. If both of these
are OK, then the program substrings off
the entire segment (this is easy: since
asterisks represent one byte, you know
how long the segment is and can use a
MID$ to get the entire segmentj. You
then GOSUB to tlie asterisk subrou-
tine. If that doesn't match, it does not
necessarily mean that there is no
match; it means that you must scan
further to see if you can find another
occurrence of the subsegment in front
of the asterisk. To do this, line 146
does a GOTO 140. If you get to line
148, it means you have found the right
segment and have masked the aster-
isks. Check it. If it is good, go back to
line 120 to find the next segment; if the
comparison is false, you don't have a
match, and so you RETURN.

Please note that there are lots of
string operations in this routine, and
string operations create garbage. If
there are hundreds of string variables
(as in an array, for example) in a large
program that uses lots of memory,
memory will need to be cleaned quite
often, which may consume a consider-

able amount of time. In most circum-
stances, however, this should not pre-
sent a problem.

If you are interested in developing
uses for this routine, I suggest you use a
very short program to get the strings
called A$ and S$, and see if it accurately
reports match/no match. Listing 2 is
just such a short test program. You can
put it in front of the Match routine to
test it. In this test program, if you want
to use the same author string again,
press return without entering anything.
To end, simply enter 'END' as the
author string. Try it with represen-
tative samples to see if it is accurate
and fast enough for your purposes.

Limitations and Modifications

When using this match routine in
my programs, I have found no cases of
the routine reporting incorrect results.
However, experimentation has shown
that the routine will give an incorrect
result if a word with an asterisk in it is
repeated and separated by ampersands,
such as

&GRE*N &GRE*N &

This will report a match if it finds just
one occurrence of the string. If the
items are separated, such as

& GRE*N & MACHINE & GRE*N &

it always reports no match. These prob-
lems are caused by the need to check
that the segments are in the right order.
They are the only limitations in the
algorithm of which I am aware. There
may be others.

As indicated above, I followed the
lead of IBM's Coursewriter in not
allowing the asterisk to mask a blank.
If you would like the asterisk to ignore
a blank as well as any other character,
change statement 162 to REM.

When items are separated by the
ampersand, they must be in the order
that they appear in A$. If order is unim-
portant, so that

& COMPUTER & MACHINE &

should give a match no matter which
order the two words are in, change
statements 134 and 144 to REM. I have
not tested the accuracy of all possible
combinations when lines 134, 144, and
162 are all chanaged to REM.

Uses for the Match Routine

There are various types of CAI. One
is "drill and practice," in which the
student is given quick, rapid-fire drill
on items that have one right answer.
Another type is called "tutorial,"
which serves as a tutor to the student,
giving practice but also supplying ex-
planations to the student. If the CAI
program is to act as an effective tutor
rather than a drill-master, it is
necessary to identify student errors and
diagnose them. Diagnostics explain the
specific error to the student so he can
understand the error, learn from it, and
— hopefully — not repeat it.

The author who designs materials
with diagnostics has two basic choices
for formatting the student's response:
some type of "objective" (or "con-
trolled") questions, such as true/false,
multiple choice, yes/no, etc.; or some
type of open-ended (or "non-
controlled") item. The controlled type
is comparatively easy to program,
although it does take time and care to
develop effective materials. But some
types of teaching activities simply can-
not be done by a controlled-question
format. As a foreign-language teacher,
for example, I want my students to use
the language forms actively, rather
than merely to identify the correct
form in a controlled format.

With non-controlled items, a stu-
dent may be asked a question to which
he responds with a sentence. It is im-
possible for an author to predict every
possible variation of vocabulary, ex-
pression, and spelling that the student
might use in his answer. Most CAI pro-
grams scan the answer, looking for a
key word or two. If the student has used

No. 57 - February 1983

MICRO

those words, the answer is considered
correct. For this reason, all the CAI
languages with which I am familiar have
some type of facility that enables the
author to scan the student response.

What a Match Routine Does

A match routine can be used for
several purposes: to scan for a key-word
or key phrase, to overlook misspell-
ings, and to detect what type of error a
student has made, which is necessary
for effective diagnostics. To do these
things, the author must be able to tell
the routine what to look for and what
to ignore (selective ignoring or masking
is what a match routine is all about]. I
use two characters (as in IBM's Course-
writer): the asterisk and the ampersand.
The asterisk ('»') indicates a "single-
character ignore;" that is, when scan-
ning to see if the student's response
matches the author's expectations, the
routine ignores the character in the
position of the asterisk. Thus, if the
author asks to match COMPUT»R, the
routine reports a match if the student
response is "computer" or
"computor" or "computir" or even
"computzr". Because the asterisk ig-
nores only non-blank characters, a
response such as "comput r" will yield

a no match. The ampersand ("&'),
which is a "multiple-character
ignore," means ignore anything and
everything (or even nothing!) in that
position. It works just like the 'wild-
card' character ' = ' used in some utility
programs, such as FID. Thus, an in-
struction such as

& COMPUTER &

tells the routine to report a match if it
finds the word "computer" anywhere
in the response.

The asterisk and ampersand can be
used together so that an instruction
such as

& COMPUT*R &

returns a match if it finds the word
"computer" or "computor" or "com-
putir" or even "computzr" anywhere
in the student response. Note that the
placement of the ampersands may be
crucial. If there is not an ampersand at
the beginning, the word must be the
first word in the response, since the
routine is not instructed to ignore
anything in front of the first word.
Similarly, if there is no ampersand at
the end, the word will have to be the

last! Several different words can be
used, separated by ampersands:

& COMPUTER & MACHINE &

will give a match only if the student
uses both words and in that order.
Some things that match are "The com-
puter is a useful machine," "My com-
puter is bigger than a sewing
machine," etc. However, "A com-
puting machine" would give a no
match ('computer' is not there) as
would "That machine is my
computer" (the words are out of order).
Figure 1 shows more examples of
strings that match or don't match.

One use for a match routine is to
find a key word or a key phrase. To do
this, the author puts the key word or
key phrase between ampersands. If it is
important that they be stand-alone
words, rather than parts of words, there
must be a space between the amper-
sands and the word; if not, then the
ampersands should not be separated.

A second use for a match routine is
to be able to ignore misspellings and
typographical errors. To do this, the
author may substitute the asterisk for
the letter(s) most likely to be misspelled.
Or, the author can use the ampersand

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MICRO

No. 57 - February 1983

to ignore several characters. Of course,
the two can be used together.

A third use for a match routine is to
find out exactly where a student has
made a mistake. In my opinion, the
most effective CM does not merely tell
the students that they have made a
mistake, but it diagnoses the error; i.e.,
it tells them what they did wrong and
offers an explanation. The only way an
author can effectively diagnose errors is
to know what the error is. Diagnosis is
comparatively easy with controlled
items; with non-controlled items it
becomes more difficult — precisely
when diagnosis is most important.

This match routine is not very fast
since it is in BASIC rather than
machine language. Putting some
Spanish CAI on my Apple, I found that
it takes about 1.4 seconds to compare
this author's string

& LE DECIMOS & QUE & SE ACUESTE &
(we tell him to go to bed) — put

English translation here, please, author!)

with this student response: "Nosotros
le decimos a Juan que se acueste tem-
prano' ' (We tell John to go to bed early) .
That is not too long, but if the student
makes some unanticipated mistake, it
takes the program even longer to work
its way through to find the error. (I
have timed the program to take as long
as five seconds in involved cases where
the match routine must be invoked
many times to analyze one sentence).
To obscure this time lapse, at various
stages I include progress messages such
as "THE SENTENCE IS INCORRECT"
when the right answer is not matched,
"FIRST VERB IS CORRECT" as the
checking continues, etc. The length of
time is urmoticeable since the process-
ing is completed before the student
finishes reading the messages.

Linking the Match Routine
To a Piogiam

I use the match algorithm as a

Figure 1: Examples of "Match"

and "No Match"

Match?

& COMPUT.R &

COMPUTER

Yes

COMPUl'lR

Yes

COMPUTING

COMPUTE OR DIE

& COMPUT&

COMPUTER

Yes

COMPUTE OR DIE

Yes

COMPUTING MACHINE

Yes

& GREEN &

GREEN FIELDS

Yes

GREENSLEEVES

GREAT SPLEEN

& GRE*N &

GREEN BEANS

Yes

A GREEN AND RED COLOR

Yes

IT IS GREAN

Yes

GRAIN

&GR&N&

GREEN FIELDS

Yes

GREENSLEEVES

GREAT SPLEEN

Yes

GROWN MAN

Yes

GROANING

&HOW&

I DON'T KNOW HOW TO DO IT

Yes

HE WENT TO THE SHOW

Yes

MITCH OWES ME MONEY

&B.T&

BYTE

Yes

BIT

Yes

BOUGHT

I BAT THIRD

Yes

& COMPUT& MACHINE &

A COMPL) TING MACHINE

Yes

A COMPUl'ER OR A MACHINE

Yes

THE MACHINE IS A COMPUIER

COMPU TING MACHINERY

COMPUIE THE COST OF THE

MACHINE

Yes

subroutine in my BASIC programs, ac-
cessing it with a GOSUB. I start it on
line 100 (see the Match Routine), ex-
tending it to line 166. (My input
routine with pre-processor is the only
thing earlier in the program. Since both
are accessed frequently, I put them as
close to the top as possible.) Because
you cannot pass arguments, you must
make assignment statements before
the GOSUB statement. The routine ex-
pects the string variable A$ (for
'Author') to have the string to be
matched; the variable S$ (for 'Student')
is assigned the student response (after
pre-processing eliminates punctuation,
compresses double blanks, and puts a
blank at each end). I usually combine
everything on one line:

A$ = "&KNI*ES&"
GOSUB100

S$ = IN$:

The match routine reports the result
via the variable R; R = if there is no
match, R = 1 if there is, and destroys
the strings A$ and S$ during process-
ing. The match routine needs to use in-
termediate strings, and some index and
pointer variables. The following
variable names are used: Zl, Z2, Z3,
Z4, Z5, Z6, Z7, Z8, Z9, Zl$, Z2$, Z3$,
Z4$, Z5$. Any values stored in these
variables when the match routine is in-
voked may well be destroyed.

Conclusion

In applications where users will be
responding with words and phrases, a
routine that masks part of the input
often is necessary to analyze that input.
The routine may scan for key words,
overlook spelling and typographical er-
rors, or find exactly where an error oc-
curs. For whatever purpose, the two
masking characters (the asterisk and
the ampersand) enable the author to
use and analyze verbal input in-
telligently to achieve the intended
results. This match routine is one tool
that can be used to do that.

Robert Phillips has B.A., M.A., and Ph.D.
degrees in Spanish. He is a professor at
Miami University, Ohio, and is Assistant
Chairman of the Department of Spanish
and Portuguese. He has been working with
Computer-Assisted Foreign Language
Instruction since 1970 and has written
CAI in PL/1, FORTRAN, APL,
Coursewriter, and BASIC. You may
contact Professor Phillips at the Dept. of
Spanish and Portuguese, Miami
University, Oxford, OH 45056.

JNoao

No. 57 - February 1983

MICRO

An Overview of
Educational Software

by George Gerhold

As a follow up to our October
education issue, this article
offers a discussion on
specialized systems designed
for educational applications.

Educational software can be classified
into three groups: applications software
— programs designed to help the users
(students) to master a particular body
of material; general systems — stan-
dard packages useful in an educational
setting; and educational systems soft-
ware — specialized languages and sys-
tems designed for educational applica-
tions. Our emphasis here will be on
educational systems software.

But let's begin with a few com-
ments about applications software.
There are vast amounts of such
material in existence (something like
10,000 hours worth for the PLATO
system alone). Much of the applica-
tions software for microcomputers is of
very poor quality, much of it is hard to
locate (it was written by a teacher for
use in a particular classroom, and a
half-hearted attempt at marketing was
made), and most of it is poorly docu-
mented. A number of publications and
organizations have attempted to ad-
dress these problems. The Microsoft
Project (Northwest Regional Educa-
tional Laboratory) is the most am-
bitious attempt, in particular their ef-
fort to establish a data base that lists
sources and reviews. It appears that
there is an obvious need for quality
control via reviews, but there are many
problems. Applications software is sup-
posed to provide individualized in-
struction, and what works well in one
setting with one group of students and
one teacher may fail in another setting.
How does one review truly individua-
lized material?

Reading reviews of applications soft-
ware is somewhat like reading reviews
of recordings of contemporary classical

music. Since there is no standard of ex-
cellence for comparison, the reviews
may tell more about the reviewer's bias
than about the quality of the product. A
number of institutions are trying to
cope with the problem by assembling
libraries for preview of programs.

There are obvious problems with
guaranteeing respect of copyright. Also,
many of these institutions have spent
their whole budget on hardware and are
relying on donated software. We esti-
mate that it will take close to 1,000
such centers to adequately cover the
country. No small supplier of software
will be able to supply that number of
free copies! A number of the textbook
publishers have entered the educa-
tional software field. Their products
tend to place heavy emphasis on the
most routine kinds of drill (heavy use
of multiple choice or numerical
answers) with elaborate record keep-
ing. These programs are protected in
ways that also prevent teachers from
customizing them for their own class-
rooms. Time will tell whether or not
the publishers will find a way to com-
bine their mass marketing approach
with the individualization that charac-
terizes the best educational applica-
tions software.

Next we turn to general systems
software with educational applications.
Word processing systems have obvious
educational utility. Current practice in
composition courses is to emphasize
the rewriting/editing process as the
part of composition that can be taught.
There are a number of schools using
word processing software in this way.
One of the problems is that many of the
word processing packages are designed
for commercial use and as such are
more complex than necessary for stu-
dent use. A student version of Wordstar
would be a worthwhile product.
{Editor's note: Memory Bank has just
released "The Bank Street Writer," a
word processor for students.) Unfor-

tunately, much of the hardware being
purchased by schools is not ideal for
word processing because of short lines
and fuzzy characters. Data base man-
agement systems could be widely used
in schools, both in individual class-
rooms and in central offices. Again,
simplified versions of business systems
should find a market here. At present
there are a number of administrative
packages on the market; for example,
gradebook, attendance, and library
packages. One of the most impressive
is the Harts III package that, in addition
to the items listed, also handles class
scheduling for a large (1,000 students)
school. Without doubt, the most widely
used packages in this class are general
language interpreters and compilers
used in programming courses. One
worthy of mention is the Interpas-
RASCAL system, an interpretative ver-
sion of Pascal plus a set of graphic and
sound programs. This system comes
with a complete cuniculum including
textbooks and student and teachers'
guides. It is cunently available from
McGraw-Hill (Gregg Division) for the
Apple n. No doubt other similar
packages will appear shortly. One final
item likely to find wide acceptance is
the disk library management system
for keeping track of programs. Disk
Master for the Apple 11 is a fine example
of this type of program.

Finally we come to systems soft-
ware designed specifically for educa-
tional applications. Again this is con-
veniently divided into three classes:
programming languages, authoring lan-
guages, and authoring systems. LOGO
is really the only language designed for
student programming. LOGO offers
many advantages for this purpose. It is
highly structured and allows long vari-
able names and procedure names. It
uses advanced techniques like recur-
sion in an elementary and natural way.
Above all, its orientation is primarily
graphic, at least at the beginning levels.

MICRO

No. 57 - February 1983

Graphic exercises offer many advan-
tages for use with beginners. The ap-
peal is sufficient to hold their interest,
and debugging is a visual process rather
than an abstract reasoning process. For
example, "the program went wrong
after drawing four line segments" is
much easier to detect than "the pro-
gram gave this wrong numerical
answer by going off after the fourth
numerical step."

LOGO is available for three dif-
ferent microcomputer systems, with
more rumored to be on the way. Three
different sources offer versions for a
64K Apple n with one disk; these ver-
sions differ only in minor ways. Texas
Instruments offers a ROM version for
the 99/4 with memory expansion.
Radio Shack offers b6th a ROM version
(16K] and a disk version [32KJ for the
Color Computer. There are significant
differences between the three systems.

The Apple versions are probably
closest to the original mainframe ver-
sions of LOGO. This is accomplished
at the cost of speed, expensive hard-
ware (remember 64KJ, and severe re-
strictions on the amount of user pro-
gram space. The Texas Instrument ver-
sion adds more colors and sprites,
which aid animation. This version of-
fers only integer arithmetic and draws

lines only by character definition, an
approach that noticeably limits the
complexity of figures that can be
drawn. The Radio Shack version re-
quires the least hardware and adds
multiple turtles. This latter feature
allows use of LOGO for illustration of
true multi-tasking and other advanced
concepts. It also provides a way for do-
ing simple animation. The Radio Shack
version offers only integer arithmetic
and eliminates all of the word and list
processing operations of the original
LOGO language. These differences re-
flect different analyses of what the
educational applications of LOGO will
finally be. Rumor indicates that there
will be a sprite version for the Apple
(requiring extra hardware) and a real
number and line drawing version for
the Texas Instrument. In considering
LOGO as an educational tool remem-
ber that it has been available for only
one year. No doubt there will be many
new applications of LOGO in the near
future.

Author languages are general com-
puter languages designed to make the
programming of instructional dialogs
easier. Author languages reflect a dif-
ferent set of priorities than more
familiar computation languages like
BASIC and Pascal. For example, an

author language makes programming
the recognition of keywords in a
response relatively easy, even when
those keywords are misspelled by the
user, but an author language has little
need for the nested loop construct
essential in number-crunching applica-
tions. Although there are a number of
author languages for large computers,
only PILOT has been implemented on a
range of microcomputers. There are
many versions of PILOT around, but
the commercial products come from
three sources. The original PILOT
came from the San Francisco Medical
Center. Nevada PILOT and Atari
PILOT are close to the original version,
but Atari PILOT has added turtle
graphics to the package. A major set of
additions to the original language were
developed at Western Washington Uni-
versity. Micropi offers versions based
on those extensions for CP/M, 6809,
TERAK, IBM, Pascal machines, and for
a number of larger mainframes. Apple
PILOT, TI PILOT, Monroe PILOT,
Color PILOT (Radio Shack), and the
forthcoming PILOT for the Com-
modore 64 are all based on the Micropi
version. IIAT offers a version of PILOT
for CP/M machines.

Author languages offer several ad-
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Programmer (or author) productivity is
much higher when using author lan-
guages. In fact programmer productivity
when using a language like BASIC for
such applications is often so low that
they are forced to adopt multiple choice
or numerical formats almost exclusively.
Thus, a related benefit of using an
author language is an increase in quality
made possible by the increase in author
productivity. Another advantage is that
a flexible instructional program written
in an author language is likely to be
much more intelligible to teachers than
the same program written in BASIC.
This is important because the best
educational software is imder revision
— based on student reactions — for
many cycles. Intelligible programs get
revised and improved; others do not.
One of the assumptions behind the
PILOT language is that it is easier to
teach an experienced teacher how to
program using an author language than
it is to teach a computer programmer
how to design good instructional
material. Experience has shown that
this is true. Now the problem is to get
the teachers enough free time to actu-
ally do it!

Authoring systems represent another
attempt to make it easier for experi-

enced teachers to generate instruc-
tional software. Authoring systems pre-
sent a menu of formats for instruction;
for example, true-false, multiple-
choice, and fill-in-the-blank. Once the
teacher has selected the format, the
authoring system builds the instruc-
tional program from the teacher's
responses to questions. Typically the
authoring system would pose a series of
questions like: what instructions do
you want to give the student, what is
the first question you want to ask the
student, what is the correct answer,
what response do you want to give to a
correct answer, where should the stu-
dent be sent after a correct answer,
what is a common incorrect answer,
etc. In some authoring systems the
teacher's input is encoded into a file; in
others the teacher's input actually
generates a PILOT-like program. There
are a variety of authoring systems on
the market. All of them work on only
one machine so there is no
transferability possible. Without ques-
tion the most elaborate is Bell and
Howell's PAS system. PAS provides the
widest range of formats and ways to in-
clude true flexibility in answer process-
ing, although the latter requires some-
thing very close to programming. PAS

also provides a variety of type styles
and some graphics. PAS also carries
what must be the record price for
microcomputer software — $15,000 ed-
ucational or $20,000 commercial, plus
a healthy yearly fee. If I were the in-
structor, I'd rather keep the money and
leam to program!

Finally we come to the area where
educational software is weakest —
graphic design. One problem is that the
people writing educational software
have no training in graphic design, so
they tend to ignore it. The other prob-
lem is that the software for graphic
design included in most development
packages is comparatively crude. Com-
puter languages often draw on common
knowledge to make learning computer
languages easier. For example, many
languages use an algebra-like syntax in
numeric assignment. The problem is
that we have no generally accepted lan-
guage for graphics that can be trans-
lated into computer terms. Both soft-
ware and hardware (e.g., graphics
tablets) solutions have been tried, but
much remains to be done. The next de-
velopment in educational software
tools probably will be in the areas of
graphics and speech generation.

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(503} 754-0237 MJCRObltS continued on page 93

MICRO

No. 57 • February 1983

Microcomputers in a College
Teaching Laboratory, Part 4

by Deborah Graves, Richard H. Heist, ThorOlsen, Howard Saitsburg

Interfacing a microcomputer to
two types of scientific
instruments is described. These
applications illustrate the
importance of commonality in
both hardware and software
design. Interfacing a
microcomputer to a scientific
instrument can enhance the
capabilities of the Instrument,
as Illustrated with a
spectrophotometer, or it can
facilitate data reduction and
increase productivity, as
illustrated with a gas
chromatograph.

In Parts I - 111 of this series (MICRO
53:53, 55:59, 56:38) we have described
how the microcomputer is used for
both data acquisition and process con-
trol in the undergraduate chemical
engineering laboratory. ^"^ So far we
have concentrated on interfacing
microcomputers directly to laboratory
experiments and replacing conven-
tional analog instrumentation with a
combination of A/D converter, micro-
computer, and printer — our universal
instrument.

A related area of application for the
microcomputer involves interfacing to
more sophisticated scientific in-
struments. There are two primary
reasons for using a computer with a
scientific instrument. The first is to
enhance the capability of the instru-
ment, and the second is to improve
operational features, such as ease and
speed of operation and data reduction.
The gas chromatograph and the spec-
trophotometer are good candidates for
microcomputer interfacing. Both find
widespread application in chemistry
and related fields, and all but the most
expensive models require the user to
spend a considerable amount of time
reducing data.

The Gas Chiomatogiaph

One of the most widely used
analytical tools is the gas chromato-
graph [GC]. The chemical engineering
department is no exception, as we
make heavy use of the GC in both
undergraduate and research labora-
tories. In the imdergraduate laboratory,
it is not uncommon for students to
generate 15 to 20 chromatograms in an
afternoon. Each of these must be
analyzed and the data processed to
reach the objective of the experiment.
The data analysis can be quite tedious
and time consuming. If a strip chart
recorder is used to record the data,
retention time and peak areas must be
measured with conventional methods.
Also, data reduction will generally be
done outside the laboratory and usually
too late to repeat any analyses that
yield questionable results. These
features of the laboratory are very un-
attractive to the student and tend to
obscure the important features of the
experiments.

These time-related problems have
been eliminated by using the micro-
computer to acquire and process the
data from GC analyses on line. Data
reduction that would normally require
hours is now done in a matter of
minutes. Consequently, oui students
are now able to devote more of their
time to the underlying conceptual
aspects of the laboratory experiments.

The hardware required to interface
the microcomputer to the GC is sim-
ple. The detector output is a voltage in
the low millivolt range, similar to the
output from thermocouples, as discussed
in Part U of this series.^ Consequently,
the A/D-convertei interface (QM-100
and signal amplifier) used for tempera-
ture measurements should be directly
applicable. Initially oui chief concern
was sampling speed since it is possible
to get rapidly changing signals (narrow

signal peaks) from the GC. However,
the QM-100 A/D converter allows
sampling rates up to 50 Hz, and this has
proven to be more than adequate for all
oior applications. The only remaining
problem was to develop a computer
program that would satisfy our needs
and be easy for the students to use.

The software package developed for
the GC system consists of both
machine-language and BASIC pro-
grams. The machine-language program
acquires and tests the data, and the
BASIC program interacts with the user
and performs data reduction. The user
interface is designed to be friendly. The
user doesn't need to be aware of the
machine-language program since the
BASIC program provides all instruc-
tions necessary to operate the system,
as well as a menu of available options
for data output. A user does not need a
computer backgrotmd to run the system.

To operate the system, the user in-
jects a sample into the GC and pro-
duces a small pressure spike by
momentarily interrupting the carrier
gas flow. This spike produces a small
output signal that causes the computer
to begin the timing for the analysis and
to look for incoming data. As the com-
ponents of the sample pass over the
detector, the computer stores the
digitized signals and indicates to the
user that it is accepting data.

After the data acquisition is com-
pleted, the user signals the computer to
begin the data analysis. The program
computes retention times and peak
areas. If there is peak overlap the peak
areas are resolved by dropping a per-
pendicular between the two adjacent
peaks. After a short time (10 to 60
seconds, depending on the size of the
data set) the user is queried as to which
results he would like to see. One option
is to display the spectrum, retention
times, and peak areas on the computer

No. 57 - February 1983

MICRO

screen. Another is to generate high-
resolution hard copy on a printer. The
screen plot is generated using the 16
PET/CBM graphic characters that com-
bine quarter-cursor elements. The linear
resolution of the screen plot is thus
twice that obtainable by simply plotting
with full size characters. The screen
plot allows previewing of data prior to
plotting on the printer. See figure 1 for
examples of the printer output.

The GC -microcomputer combina-
tion has been used successfully for over
two years and has had a significant im-
pact on the laboratory program. It has
provided a convenient method of data
reduction and demonstrated the utility
of the microcomputer as a laboratory
tool. In addition, by streamlining the
experiments that rely on the GC for
chemical analyses, the microcomputer-
GC system has improved our ability to
handle large numbers of students in the
laboratory program. This point has
been most important since increased
enrollments have had a profound im-
pact on our laboratory operation.

The Spectiophotometei

Another important, commonly used
analytical instrument is the spectro-
photometer. Our department uses spec-
trophotometers primarily as research
tools, although they have been used in
the undergraduate laboratories to a
limited extent.

The spectrophotometer presents the
user with problems similar to those of
the GC. The measxirement of an optical
absorption spectrum produces a lot of
information that must be aiialyzed and
then converted to another form [such
as absorbence, transmittance, or ex-
tinction) to be of direct use. If the spec-
tral scan covers a wide range of wave-
lengths, data reduction can be quite
time consuming. As with the GC, there
are expensive accessories that will do
most of the work, but these devices are
not available in all laboratories and
certainly not in most teaching
laboratories.

Most spectrophotometers use a
photocell or a photomultiplier tube as a
detection device, so the output signal is
a current. Normally this is passed
either to a chart recorder or a display of
some sort, which converts the signal to
a numeric representation. Since the out-
put current of the detector can easily be
converted to a voltage (see Part II of this
series!, it is a simple matter to use the
QM-100 A/D converter and an ampli-

WTEi

S>M>LE:

CSNCNTS;

RT< 1
RT< 2

>> 4S S. flC 1

^ 57 S. (X 2

' 481S
< 2318

SCaLEO SKCTfUti
SCBLIN6 raCTOR- .85

OHTE:
COtCNTS:

RT( 1 )« 34 S. (K 1

RT( 2 ^ 48 S. (K 2

RT< 3 )« 52 S. (K 3

RT< 4 >» 75 S. «< 4

SCALED SPECTRUM:
SC«ILIH6 FOCTOR- 1.85

1725
1788
2943
1951

Figure 1: High-resolution hard copy from two gas chromatography experiments. The
first illustrates the chromatograph of a two-component mixture, and the second, a
four-component mixture. The retention times and peak areas are Indicated at the top
of each plot. The chromatograms were obtained with a Carle Model 8700 gas
chromatograph Interfaced to a PET/CBM microcomputer and Trendcom 100 dot-
matrix printer, as described In the text.

fier to interface the spectrophotometer
to the microcomputer. In this case, as
with the GC, the hardware re-
quirements are simple. The only sig-
nificant problem was the development
of the necessary software.

The software requirements for data
acquisition with a spectrophotometer-
computer system are not very different
from those already discussed for the
GC. The computer must be signaled
when data collection is to begin, and it
has to store the acquired data for pro-
cessing when the analytical scan is
finished. It is necessary to keep track of
the time and the wavelength scan rate
so the wavelength scale can be cali-
brated properly. Another requirement
is that high-resolution hard copy of the
absorption spectrum must be available
for further analysis.

The BASIC portion of the program
package, which interfaces with the user
and performs the calculations, was
specific to this application and had to
be written in its entirety. Because of
the similarity in the requirements of
the data acquisition routine, however,
it was possible to modify the machine-
language code from the GC program (by
deleting parts specific to the GC and
adding a few routines for handling the
timing) and apply it to the spectro-

photometer system. This commonality
among applications in both software
and hardware requirements is impor-
tant. It occurs frequently, and recog-
nizing it can save a great deal of time
and effort.

Since the spectrophotometer gener-
ally scans a wavelength range during an
analysis, it is important to coordinate
the sampling rate and the wavelength
scan rate. We chose to use a timer
available on one of the input/output
chips (6522) of the PET/ CBM com-
puter. With this timer it is easy to
measure time intervals precisely and
have the microprocessor interrupted at
the end of each interval so that it can
sample the spectrophotometer output.
By knowing the scan rate and keeping
track of the number of sample points
collected, the wavelength for each
point can be determined. Once the
computer has collected the data, absorb-
ence or transmittance is easily calcu-
lated. Details are available in the litera-
ture concerning the PET/CBM input/
output ports"' 5 and the 6522.'

One very significant advantage of
this system over the use of a chart
recorder is that the data can easily be
stored, either internally or on an exter-
nal mass storage device. Therefore, it is
a simple matter to convert a single-

MICRO

No. 57 • February 1983

***** *****

m il

SPECTRUM BESULTS

DRTE: !e.'3e-S!
SflHPLEi BENZENE UflPOR
REFERENCE! filR
CONCENTRBTION: 1
PRTH LENSTH: :
SLITS: 58 NICRONS
Lor TYPE; DEUTERIUK

PNT uoLTneei Tee

OMItTER RflNBEi IBE-B?
SCHH ROTE.- 3 flH6STR0MS/SEC.
BES. GF SCflH! 2388 RNSSTROME
HIDTH OF SCflH. 4ee flHBSTHOHS
PHSSTROHS PER OVJ.: a 3!

aio

iio

X Inm)

Figure 2: The ultraviolet absorption spectrum of benzene vapor at room temperature.
The spectrum was obtained using a GCA McPherson single-beam spec-
trophotometer Interfaced to a PET/CBM microcomputer and Trendcom 100 dot-
matrix printer.

beam spectrophotometer into what is
effectively a dual-beam device. The
basic requirement is that the analysis
be run twice, first in the reference
mode, and then in the sample mode.
An example of this type of application
is shown in figure 2. This absorption
spectrum of benzene was taken at room
temperature with a single beam GCA
McPherson spectrophotometer. The
units of the wavelength scale are 4.56
Angstroms/division; the ordinate is in
absorbence units. The high spectral
resolution is evident and comparable to
that obtained from much higher -priced
instruments. Individual portions of an
absorption spectrum can be selected
and magnified by changing the scan
rate and the wavelength range and re-
peating the scan. Dual-beam spectro-
photometers are generally more de-
sirable than single beam devices, but
they are also much more expensive.
Thus, the interfacing of a microcom-
puter to the spectrophotometer re-
sulted in enhanced capability without
significant additional expense.

References

1. Saltsburg, H., Heist, R.H., and
Olsen, T., Miciocomputeis in a Col-
lege Teaching Laboiatozy — Pan 1,

MICRO, No.53, October, 1982,
pg. 53.

2. Heist, R.H., Olsen, T., and
Saltsburg, H., Miciocomputeis in a
College Teaching Laboiatozy — Pan
2, MICRO, No. 55, December, 1982,
pg. 59.

3. Olsen, T., Saltsburg, H., and Heist,
R.H., Miciocomputeis in a College
Teaching Laboiatozy — Pan 3,
MICRO, No. 56, January, 1983,

pg-

4. West, R.C., Piogiamming the PET/
CBM, The Refeience Encyclopedia
foi Commodoie PET/CBM Useis,
Compute! Books, Greensboro, N.C.,
1982.

5. Hampshire, N., The PET Revealed,
Computabits Ltd., Somerset,
England, 1980.

6. See, for example, Dejong, M.L., Pio-
giamming and Intezfacing the 6502,
with Expeiiments, Howard W. Sams
&. Co., Inc., Indianapolis, 1980;
Zaks, R., 6502 Applications Book,
Sybex, Berkeley, 1979.

You may contact the authors at the
Department of Chemical Engineering,
University of Rochester, Rochester, NY

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iMCRO

No. 57 - February 1983

MICRO

JMCdO

CoCo Bits

By John Steiner

This month's column looks at tech-
niques that allow you to interface your
machine-language routines with BASIC .
The Color Computer memory map,
published by Tandy, leaves many un-
documented locations. Hopefully I can
put a few items in their correct places.

To demonstrate the use of a RAM
hook, I have included a list-pager pro-
gram. [More on this later.) If you know
any locations of RAM hooks, or ad-
dresses of particular BASIC functions
in ROM, please contact me.

Ben Farmer of Charlottesville, VA,
sent the following information on a
print-routine hook: locations 159, 160,
and 161 are called during print to
screen or printer; and locations 410 to
412 seem to hook to the keyboard after
each BASIC keyword. Mr. Farmer also
points out that there is a compatibility
problem with EDTASM + and the 8-bit
printer driver distributed by Radio
Shack to people with 1.0 ROM. The
driver is required to work with the
DMP-100 printer, yet it won't work
with the assembler. If anyone has found
a solution to the problem, let me know.

While I am on the subject of RAM
hooks, I have a routine that interfaces
with the LIST and LLIST command to
page a list on the screen (see listing .1).
Before loading the program, enter
CLEAR 200, &H7FE5. This protects
the routine from BASIC. Load the pro-
gram by reassembling or POKEing the
data into memory. To activate the
routine, the hook at locations 383, 384,
and 385 is used. These locations con-
tain an RTS, and 383 is accessed after a
LIST or LLIST. If an instruction is
found, it can be executed. In this case, a
JMP to the routine will be executed. As
assembled, the page lister is written to
fit at the top of a 32K machine. With
one exception, the program is written
in position-independent code. If you
move the program, the location
LINCNT must be defined to a valid
RAM location.

The program lists 14 lines to the
screen and stops, waiting for a key-
press, after which the next 14 lines are

BATTERY _L
OR ^
POWER 4-
SUPPLY -

GROUND
THIS POINT

i REMOTE
, . ^ JACK

X j_ I r-T-^

"mi

25A684

listed. To hook the program to BASIC,
after loading the routine, enter:

POKE 383, &H7E : POKE 384, &H7F :
POKE 385, &HE7

If you do not have extended BASIC, you
will have to convert the hex numbers to
decimal. Load a BASIC program and do a
LIST. (If you do an LLIST, you will find
that the program does not stop after 14
lines, but continues until completed.)
The routine is called just before
each line in a listing. The opcode $7E
causes a JMP to the start of the program
at $7FE7. The routine checks location
$006F (DEVNUM), which determines
printer or screen status. If $6F contains
$FE, the list is going to the printer; a
$00 indicates the screen is the destina-
tion of the print. When anything but
zero is found, control returns to BASIC.
If screen printing is being done, $7FE6
is incremented by 1 . A CMP tests to see
whether or not the fourteenth line has
been printed. If not, control returns to
BASIC. You can change the number of

MECHANICAL
SWITCH IN
^ RECORDER

CUT FOIL AT Xs

TO
RECORDER

lines printed by changing the data
in $7FF2.

When 14 lines have been printed,
control jumps to the GETKEY routine
in BASIC. The program loops while
waiting for a keypress, after which the
count is reset to zero and control
returns to BASIC.

Other applications for this particu-
lar RAM hook come to mind. For exam-
ple, it would be easy to supply a line
feed after the BASIC -generated caniage
return for those printers that need it.

Bob Gilbertson of Fargo, ND, pro-
vided me with the circuit in figure 1.
This circuit is a modification that
allows the connection of high-current-
drain cassette recorders to the light-
duty relay inside CoCo. If you use a
standard Radio Shack series recorder,
you don't need this modification; but if
you can't bear to spend money on a
new recorder while an older machine
just sits on the shelf, you can use this
circuit. The RS recorder has a very light
current drain, and the relay provided is
more than adequate. If you use a re-
corder with too much current drain.

00100 «PAGER PROGRAM

00110 «JOHN STEINER

00120 «NOV. 8

1982

00130 ORG J7FE6

00140 LINCNT EQU J7FE6

00150 DEVHraw EQU ?6F

7FE6

00160

FOB MO

7FE7 OD

00170 START

TST DEVNUM

CK FOR LLIST

7FE9 26

00180

BNE OUT

IF SO THEN GO

7FEB 7C

7FE6

00190 LINING

INC LINCNT

ADD 1 TO LINE

7fEE B6

7FE6

00200

LDA LINCNT

7FF1 81

00210

CMPA ||I$0E

SCREEN FULL?

7FF:) 26

00220

BNE OUT

IF NOT THEN GO

7FF5 AD

AOOO

00230 LOOP

JSR [JAOOO]

GO GET KEYPRESS

7FF9 AD

00240

TSTA

CHECK FOR KEY

7FFA 27

00250

BEQ LOOP

IF NO KEY THEN tfAIT

7FFC 7F

7FE6

00260 RESET

CLR LINCNT

SET LINE COUNT TO ZERO

7FFF 39

00270 OUT

RTS

MICRO

No. 57 - February 1983

CoCO Bits (continued)

the relay might stick closed and the
recorder will not stop at the end of
SAVES and LOADs.

Bob's circuit places a PNP transistor
in series with the power supply. The
computer relay switches the transistor,
which in turn switches the recorder.
The circuit is representative of most
portable cassette recorders. All wiring
indicated exists within the cassette
recorder itself; only the transistor and
IK resistor are added to the circuit. The
Xs indicate where a wire or foil should
be cut. The jack assembly indicated is
the motor remote control jack. Cut the
lines as shown and iijstall the transistor
and resistor. (If your cassette recorder is
positive ground instead of negative
ground, as in the schematic, use a
suitable NPN transistor.)

The circuit works by current flow-
ing through the base lead, base bias
resistor, and remote relay switch inside
the computer. Although a transistor
number is specified, almost any
general-purpose PNP transistor will
work. Choose one with a collector cur-
rent at least twice the normal current
draw of your particular cassette re-
corder. The switching current is quite
small and will keep the relay from
sticking closed.

When you finish the modification,
you can test its performance with the
following information. BASIC has two
routines in ROM that control the con-
dition of the cassette motor: MOTOR-
OFF is located at $A7E9, and MOTOR-
ON is located at $A7CA. EXEC
SlHA/CA turns on the motor, and
EXEC &HA7E9 turns it off. Another
way to control the relay is with a POKE
to the PIA at 65313. POKE 65313, 60
turns on the motor, and POKE 65313,
52 turns if off. Of course, you could just
type MOTORON or MOTOROFF, but
that wouldn't be nearly as much fun.

Next month, I will take a look at
some more RAM hooks and present
more CoCo news. If you have anything
to contribute, contact me at the address
below, or through MICRO.

You may contact the author at 508 Fourth
Avenue ^fW, Riverside, ND 58078.

iMCftO

MICRObitS (Continued from page 88)

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No. 57 - February 1983

MICRO

S llilLNTIINeir€N C€/HIPILirilNe S

B
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B

Softlights

By Fred Huntington

Time to tell you about a nitty little program
that s been around a while that deserves some
mention. The Menu Generator is an excellent
program that everyone should use on every
disk to create a HELLO program to take the
typing out of running programs.

It creates menus quickly and painlessly. The
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change without notice.

MICRO

No. 57 - February 1983

iSMCftO

Apple Slices

By Tim Osborn

This month's program, BUILDIT,
demonstrates how programs external to
VisiCalc can create and access VisiCalc
worksheet files. Both VisiCalc novices
and pros will learn from the following
discussion.

VisiCalc uses three file formats for
data storage: DIF (Data Interchange
Format|, standard worksheet files, and
print format files. DIF is an excellent,
well-documented communication aid
that many packages use to send and
receive information to and from
VisiCalc. But, because DIF is designed
for flexibility, it can be used indepen-
dently of VisiCalc. To make DIF
general and flexible, it was necessary to
remove the formulas from the work-
sheet, storing only the results of these
formulas instead. The print files just
store an image of the worksheet and,
like DIF, do not include formulas. To
save formulas it is necessary to use the
"/SS" command, which creates a stan-
dard worksheet file.

After some investigation I found
that these worksheet files are no more
than a VisiCalc EXEC file that contains
the data in the worksheet just as you
would type it in. For example, the
following worksheet

1 ALPHA

2 BETA

3 GAMMA

10
5
5

(where B3 = Bl - B2 (GAMMA =
ALPHA - BETA) ) would be stored as
shown in figure 1 .

With this method you could enter
this worksheet into VisiCalc from the
keyboard. The only unexpected thing is
the last entry. The /X appears to be an
undocumented VisiCalc command.
The "/X-" tells VisiCalc to set the
cursor direction to horizontal. The
"/X>A1:" tells it to make Al the
upper left-hand corner of the screen.
The " > Al:" sets the cursor at Al.

With this information I was able to
write BUILDIT — a VisiCalc template
building aid. BUILDIT builds account-
ing worksheets that itemize entries
vertically; the categories they belong to
are produced horizontally. BUILDIT
prompts the user for the categories and
iems. The relationship between the
various items is described to BUILDIT
by placing a relationship operator in
front of each item as it is entered.
BUILDIT accepts four types of
operators:

1. A summable group member (a
member in a list of items that pro-
duces a sum) signified by a " + " in
the first character position. There
must be at least two members of any
summable group, each member must
be preceded by a " + ", and the Mst
must be terminated with an " = "
item entry (see below).

2. A stand-alone sum (an item to be
entered as a lump sum rather than
itemized) signified by a "/" in the
first position of the item entry.

3. A sum, signified by an " = " in the
first character position of the item.
When BUILDIT encounters a sum
following a summable group, it sets
the template up to place the total of
the preceding group in the row of
this sum for all categories. If the sum
is not immediately preceded by a
summable group it sets the template
up to sum the last two items entered
that began with a "/", " = ", or a
"-" and stores the result in this
row for all categories. If two items to

sum were not previously entered, an
error message will be produced and
the entry will not be accepted.
4. A difference, signified by a " - " in
the first position of the entry. A dif-
ference takes the last two items that
began with a "/", " -", or an " ="
and sets the template up to subtract
the last item (highest numbered,
lowest down in the worksheet) from
the second to the last, storing the
result in this row.

An Example

Let's say you want to set up a work-
sheet to handle sales (disks -i- books)
less expenses (fixed + variable), com-
pute the gross income, subtract taxes,
and compute the net income. You also
want to break down the worksheet by
the first three months of the year
(January through March) with a grand
total column for the three months.

BUILDIT prompts you first to enter
the categories in the category
maintenance mode. You just enter each
category (JAN., FEB., and MAR.,) one
at a time. There is no need to enter a
grand total category because BUILDIT
always generates it for you. When you
are done entering categories just enter
"Q" for quit (you are prompted for this
in case you forget], and BUILDIT will
give you a chance to make any editorial
changes in the category edit mode.

When you are done editing the
categories just enter "Q" and BUILDIT
will enter the item maintenance mode.
BUILDIT then prompts you to enter

Figure 1

>B3:-l-Bl-B2

Goto B3 and put the formula Bl - B2 there.

>A3:" GAMMA

Goto A3 and put the label "GAMMA" there.

>B2:5

Goto B2 and put the value 5 there.

>A2:"BETA

Goto A2 and put the label "BETA" there.

>B1:10

Goto Al and put the value 10 there.

>A1: "ALPHA

Got Al and put the label "ALPHA" there.

/Wl

Set global parameter - one window.

/GOC

Set global order of recalculations to columns.

/GRA

Set recalculations on automatic.

/GC9

Set column width to 9 characters.

/X-/X Al: Al:

See below. See text.

No. 57 - February 1983

MICRO

Apple Slices (continued)

item number 1. Item 1 would be
DISKS, which is one source of SALES (a
member of the summable group
SALES]. Inform BUILDIT of this by
entering "+ DISKS". Next you enter
"+ BOOKS" to tell the program that
"BOOKS" is the second member of
this group. Entering "= SALES" tells
the program to set the worksheet to
total the "DISK" and "BOOKS" en-
tries and place the result in "SALES".
The next three entries follow the same
logic: 1, "+FIX. EX.", 2. "-i-VAR.
EXP.", and 3. "=TTL EXP." (FLXED
EXPENSE + VAEJABLE EXPENSE =
TOTAL EXPENSE).

The gross is the difference between
SALES less TOTAL EXPENSES, so the
next entry would be " -GROSS". The
next item, taxes, is not itemized or
computed so it is considered a stand-
alone sum. Taxes would be entered as
"/TAXES". The only thing left to do is
compute the net income, which is
GROSS - TAXES. The net income
item would thus be entered as
"-NET".

Now enter "Q" to end item
maintenance and enter item edit mode

Figure 2

A B

1 JAN.

FEB.

MAR.

GRAND TTL.

2 DISKS

@SUM(B2...D2)

3 BOOKS

@SUM(B3...D3)

4 SALES @SUM|B2.

.B3|

@SUM|C2.

.C3|

@SUM(D2.

.D3)

@SUM[B4...D4)

5 FIX. EXP.

@SUM(B5...D5J

6 VAR. EXP.

@SUMlB6...D6i

7 riL.EXP. @SUM(B,5.

.B6)

@SUM(C5.

.C6)

@SUM(D5.

.D6|

@SUM(B7...D71

8 GROSS +B4-B7

+ C4-C7

+ D4-D7

@SUM|B8...D8)

9 TAXES

@SUM(B9...D9)

10 NET +B8-B9

+ C8-C9

+ D8-D9

@SUM(B10...D10)

where you can make any editorial
changes. When you are done editing,
enter "Q". You will then be prompted
to enter a file name to save the work-
sheet/template. After the program has
finished writing out your file, run
VisiCalc and use the "/SL" command
to load the worksheet/template. See
the template in figure 2 (I have replaced
the zeros with the formulas for the
given worksheet coordinate). Notice
that the operators are stripped off from
the items and the grand total column is
automatically generated.

BUILDIT is fully interactive and all
relationships are validated up front. If

they are not correct, you are told which
operators would be valid. You are
always prompted and never left won-
dering how to respond. It is simple to
use (only four operators] but is de-
signed for a limited number of applica-
tions. It is designed for accounting ap-
plications where only sums and dif-
ferences are used. With modifications
it could be made to handle all but the
most complicated worksheet/tem-
plates. Perhaps as important as its
application, is the fact that it
demonstrates how programs external to
VisiCalc can be used to create VisiCalc
templates.

Listing 1

10 GOSUB 1000: REM INITIALIZE

15 AflY$ = "CATEGORY" .■PROCESSJ = "MAINTENANCE"

20 GOSUB 2000: REM GET + EDIT CATEGORIES

21 FOR J = 2) TO NUM:CT$(J) = IN?(J): NEXT

22 NC = NUM: REM SAVE NUMBER OF CATEGORIES
25 AflY$ = "ITEM": PROCESS? = "MAINTENANCE"

30 GOSUB 2000: REM GET + EDIT ITEMS

31 FOR J = TO mjM;IT$(J) = IN$(J): NEXT

32 NI = NUM: REM SAVE NUMBER OF ITEMS
50 GOSUB -tOOO: REM BUILD FILE

60 PRINT CD? "CLOSE ";FILE$

70 END

1000 CDS = CHR$ (4): HOME

1010 DIM INJ(60): DIM CT$(60).- DIM IT$(6el)

1020 FOR K = TO 8: READ MSG$(K) : NEXT

1500 RETURN

2000 J = 2l:N0DE ^ i

2005 GOSUB 2010: GOTO 2015

2010 LN = (40 - ( LEN (AfiYS)

2011 HOME : FOR X = 1 TO LN
INVERSE : PRINT ARY$;"
IF J = 6«l THEN HTAB 9

+ LEN (PROCESS?))) / 2

PRINT " ";: NEXT :
"; PROCESS?: NORMAL : RETURN

VTAB 23:
INVERSE : PRINT "MAXIMUM ";ARY?i" REACHED":
FOR X = 1 TO 2000: NEXT X: NORMAL : GOTO 2028
HTAB 2: VTAB 10: PRINT "ENTER ";: INVERSE :
PRINT "Q";: NORMAL : PRINT" TO END ";
ARY?;" MAINTENANCE"

HTAB 2: VTAB 12: PRINT ARY$;" NUMBER ";J + 1;:
INPUT " NAME ";IN?(J)

IF IN?(J) = "" THEN GOSUB 2010: GOTO 2015: REM DONT ALLOW NULL
IF IN?(J) = "Q" AND J = THEN INVERSE :
HTAB 1: VTAB 22: PRINT "YOU MUST MAKE AT LEAST ONE ENTRY";:
NORMAL : FOR K = TO 2000: NEXT K: GOSUB 2010: G0TO2015
IF IN?(J) = "Q" THEN IN$(J) = "": GOTO 2028
IF ARY? = "ITEM" THEN GOSUB 7000:
REM CHECK FOR "+" "-" "/" OR "="
2027 J = J + 1: HTAB 12: VTAB L2: GOSUB 9000: GOTO 2005
IF ARY? = "CATEGORY" THEN GOSUB 2010: GOTO 203^
IF NODE = 3 OR NODE = 6 THEN GOSUB 2010: GOTO 2034

2015

2016

2017

2020
2021

2022
2025

2028
2029

Listing 1 (Continued)

2030 GOSUB 9100: GOTO 2017: REM DISPLAY ERROR MSG+CONT.

2034 HTAB 5: VTAB 10: PRINT "EDIT ";ARY?;:
INPUT " (Y)ES OR(N)0 ";A?

2035 NUM = J: REM SAVE NO. OF ENTRIES

2036 IF LEFT? (A?,l) = "Y" THEN GOSUB 2500: GOTO 2040
2038 IF LEFT? (A?,l) <> "N" GOTO 2034
2040 RETURN
2500 NUM = J: REM SAVE NUMBER OF ENTRIES

2502 PROCESS? = "EDITING"

2503 GOSUB 2010: VTAB 2: HTAB 1:SP? = " "
FOR I = TO NUM STEP 3
IF I = 9 THEN SP? = " "
IF IN?(I) = "" THEN GOTO 2535
HTAB 1: PRINT I + 1;SP?; LEFT? (IN?(I),9);
IF IN?(I + 1) = "" THEN GOTO 2535
HTAB 14: PRINT I + 2;SP?; LEFT? (IN?(I + 1),9);
IF IN?(I + 2) = "" THEN GOTO 2535
HTAB 28: PRINT I + 3;SP?; LEFT? (IN?(I + 2), 9)
NEXT I

VTAB 23: HTAB 1: PRINT "CHANGE NO.
INVERSE : PRINT "Q";: NORMAL :
PRINT " TO END ";: INPUT "";A?
IF A? = "Q" THEN RETURN

2550 LN = LEN (A?):GD? = "Y":ZRO? = "Y"
2560 FOR I = 1 TO LN:MD? = HID? (A?, I,
2565 IF MD? > "0" AND MD? < ":"

THEN ZRO? = "N": GOTO 2575
2567 IF MD? = "El" GOTO 2575
2570 GD? = "N":I = LN: REM REQUEST IS NOT NUMERIC

2575 NEXT

2576 IF GD? = "N" THEN MSG? = "NUMERIC": GOTO 2580

2577 IF ZRO? = "Y" THEN MSG? = "NON ZERO": GOTO 2580

2578 GOTO 2595

2580 VTAB 23: GOSUB 9000: VTAB 23: HTAB 1: PRINT "INPUT ";

MSG?;" ";ARY?;" ";: INPUT "";A?: GOTO 2545
2595 NUM» = VAL (A?): REM CONVERT TO NUMERIC
2600 IF NUM» > NUM THEN VTAB 23: GOSUB 9000:

VTAB 23: INPUT "REENTER, TOO HIGH ";A?: GOTO 2545
2602 IN? = IN?(NUM» - l)

(Continued)

2505
2506
2507
2510
2515
2520
2525
2530
2535
2540

2545

.ENTER

,1)

MICRO

No. 57 - February 1983

Listing 1 (Continued)

2605 VTAB 23: GOSUB 9000: VTAB 23: HTAB 1:

PRINT "CHAMGE ";AHY$;" TO ";: INPUT "";IN$(HU«* - l)
2610 IF AHYJ = "CATEGORY" THEN GOTO 2503
2612 GD$ = "Y":NODE = i

2615 FOR J = el TO NUM - 1: GOSUB 7000:
IF GD$ = "N" THEN GOTO 2620

2616 NEXT

2617 IF NUM* <> NUM GOTO 2620: REM SEE IF LAST ITEM CHAJJGED

2618 IF (NODE = 3 OR NODE = 6) THEN GOTO 2620

2619 GD$ = "N": GOSUB 9100: FOR K = TO 4000: NEXT K:

REM DISPUY ERROR MSG + DELAY

IF GD? = "N" THEN INj(NUMi - 1) = IN$

GOTO 2503

DIM FRM$(NI,3): FIRST = - 1:LAST = -1

FOR K = 8! TO NI - 1;LT$ = LEFT? (IT?(K),1)

2620
2700
4000
4010
4015
4020
4060
4070
4072

IF LT$

IF LT?

IF LT? = "/"
4075 LAST = K
4077 NEXT : REM
4080 GOTO 4300
4100 IF LAST >
4105 FOR L = K ■
4110 IF LEFT? (IT?(L),1)
4112 NEXT

4115 FRM?(K,1) = "gSUM("
4120 FRM?(K,2) = STR? (L
4130 FRM?(K,3) = STR? (K
4l40 RETURN
4150 FRM?(K,1)

AND LAST = - 1 GOTO 4077
THEN FIRST = LAST: LAST =
THEN GOSUB 4100
THEN GOSUB 4200
THEN FIRST = LAST

1: GOTO 4077

- 1 THEN GOTO 4l50
1 TO STEP - 1
< >

3)
1)

+" THEN GOTO 4115

":FR«$(K,2) = STR? (FIRST + 2)

+ "+":FRM?(K,3) = STR?(LAST + 2)
4170 FIRST = LAST: RETURN
4200 FRM?(K,1) = "+":FRM?(K,2) = STR? (FIRST + 2)

+ "-":FRM?(K,3) = STR?(LAST + 2)
4210 FIRST = LAST: RETURN

4300 HOME : VTAB 4: INPUT "ENTER FILE NAME ";FILE?: GOSUB 11000

4301 IF FILE? = "" GOTO 4300

4302 ONEHR GOTO 4305

4303 PRINT CD?"DELETE ";FILE?

4304 PRINT CD?"0PEN ";FILE?: GOTO 4306

4305 PRINT CD?"OPEN "jFILE?: CALL 768: REM REPAIR ONERR DAMAGE

4306 FOR K > NI - 1 TO 1^ STEP - 1

4307 COL = NC + 2: GOSUB 4900:R0tf? = STR? (K + 2) :

4308 A? = ">" + COL? + ROW? + ":«SUM(B" + ROW? + "..."

4309 COL = NC + 1: GOSUB 4900:A? - A? + COL? + ROW? + ")"

4310 GOSUB 5000: REM WHITE RECORD
4315 FOR L = NC - 1 TO S( STEP - 1

4320 COL = L + 2: GOSUB 4900: REM FIGURE LITERAL COLUMN NAME

4325 IF FRM?(K,1) = "" THEN 4340

4330 A? = ">" + COL? + ROW? + ":" + FRM?(K,1)

+ COL? + FRM?(K,2) + COL? + FRM?(K,3)
4335 GOSUB 5000: REM WRITE RECORD
4340 NEXT : REM L
4345 A? = ">A" + ROW? + ";" + CHR? (34)

+ RIGHT? (IT?(K), LEN (IT?(K))- 1)
4350 GOSUB 5000: REM WRITE

4355 NEXT : REM K

4360 COL = NC + 2: GOSUB 4900

4365 A? = ">" + COL? + "1:" +

CHR? (34) + "GRAND TTL"

4370 GOSUB 5000

4375 FOR K = NC - 1 TO el STEP

- 1

4380 COL = K + 2: GOSUB 4900

4385 A? = ">" + COL? + "1:" +

CHR? (34) + CT?(K)

4390 GOSUB 5000: NEXT

4400 RETURN

4900 IF COL > 52 THEN COL? =

"B" + CHR? (COL + 12): GOTO 4915

4905 IF COL > 26 THEN COL? =

"A" + CHR? (COL + 38) : GOTO 4915

4910 COL? = CHR? (COL + 64)

4915 RETURN

5000 PRINT CD?"WHITE ";FILE?

5005 PRINT A?: RETURN

7000 LFT? = LEFT? (IN?(J),l)

7010 IF NODE = el GOTO 7100

7015 ON NODE GOTO 7200,7300,7400,7500,7600,7700,7800,7900

7100 IF LET? = "+" THEN NODE = 1: RETURN

7105 IF LFT? = "/" THEN NODE = 3: RETURN

7110 GOTO 8000: REM SEND ERROR MESSAGE

7200 IF LFT? = "+" THEN NODE = 2: RETURN

7210 GOTO 8000

7300 IF LFT? = "+" THEN RETURN

7310 IF LFT? - ">" THEN NODE = 3: RETURN

Listing 1 (Continued)

73 111 GOTO 8000

7400 IF LFT? = "+" THEN NODE = 4; RETURN

7410 I? LFT? = "/" THEN NODE = 6: RETURN

7420 GOTO 8000

7500 IF LFT? - "+" THEN NODE = 5: RETURN

7510 GOTO 8000

7600 IF LFT? = "+" THEN RETURN

7610 IF LFT? = "=" THEN NODE = 6: RETURN

7615 GOTO 8000

7700 IF LFT? = "+" THEN NODE = 7: RETURN

7705 IF LFT? = "/" THEN RETURN

7710 IF LFT? = "=" THEN RETURN

7715 IF LFT? = "-" THEN RETURN

7720 GOTO 8000

7800 IF LFT? = "+" THEN NODE = 8: RETURN

7805 GOTO 8000

7900 IF LFT? = "+" THEN RETURN

7905 IF LFT? = "=" THEN NODE = 6: RETURN

8000 HTAB 1: VTAB 22: GOSUB 9000

8005 HTAB 1: VTAB 22: INVERSE : PRINT "NUMBER ";

J + 1;"'S 1ST CHAfi. MUST BE ";MSG?(NODE) : NORMAL

8010 FOR K = 1 TO 3500: NEXT K
8012 J = J - 1:GD? = "N"

8015 RETURN

9000 PRINT " ";

9010 RETURN

9100 HTAB 1: VTAB 22: INVERSE : PRINT

"1ST CHAR OF LAST ITEM MUST BE =,/ OR -";: NORMAL

9105 RETURN
10000 DATA "+ OR /","+","+ OR =","+ OR /",

"+","+ OR =","+, /, = OR ","+","+ OR ="
11000 FOR X = 768 TO 777: READ XX: POKE X,XX: NEXT
11002 RETURN
11005 DATA 11^4,168,11^4,166,223,154,72,152,72,96

iMCftO

ADVANCED

" ii .ii ;!r

Zoom HiRes Graphic Printing
for Apple Computers

Print front or back view of either or both screens
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Selectable printing densities for many printers
Easily place zoom viewport using on-screen crosshairs
Large range of scale factors, independently selected
Load files to either screen in just 5 l<eystrol<es
Type upper/lower case English or Greek text on screen
Attach screen dump to your own programs, complete
details

Real Apple II DOS 3.3 format — Unprotected backup
with COPYA

Supports over 70 dot matrix and letter quality printers
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Also works with the Basis and Franklin Computers
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513/426-3679

HlBPt

Dealer Inquiries
Invited!

No. 57 - February 1983

MICRO

Apple Slices icommr

item number 1. Item

DISKS, which is one •■

member of the

SALES). Inforr-

entering " + '

"+BOOK

"BOO''

this

»f

accepts simple to complex sentences, but works best with
shorter ones.

lus, 48K

BeimuiiL, v.,..! ^

Description: The product provides the capability to create
and manipulate large lists of information. List manage-
ment is performed by high-speed search and sort routines.

Pluses: The system is expandable in that it will operate
with from one to eight disk drives on line, providing
management of up to 24000 records (4000 characters/
record) of data. Built-in features permit printing form
letters, mailing labels, and envelopes. A special feature for
list backup is provided.

Minuses: You can use the program with only one disk
drive, which makes it possible to destroy the program
disk. The system should have been designed to prevent
this rather than risk user forgetfulness. The company says
only one list can be stored per disk because of the need to
store large lists, but I think a multiple short list per disk
option should have been built in. Neither of these prob-
lems are serious; the product is quite usable.

Documentation: Adequate. Numerous examples are pro-
vided instead of explanation.

Skill level required: The user needs exposure to the prob-
lems of list management to get maximum utility from this
product.

Reviewer: Chris Williams

Product Name: ESTHER

Equip, req'd: 64K TRS-80 Color Computer

One disk drive, FLEX DOS
Price: $54.95, $74,95 with source

Manufacturer: Frank Hogg Laboratory

770 James St.

Suite 215

Syracuse, NY 13203
Author: Dale Puckett

Description: ESTHER shows how a computer is capable of
artificial intelligence. ESTHER will remember your name
and ask you questions in an effort to get you to unload
some of your problems. If you want to show your friends
what your computer can do, ESTHER will help break the
ice. But tell ESTHER to "shut up!" and the program will
end. It is written in assembly language and the responses
are much faster than a similar program in BASIC. ESTHER

Pluses: ESTHER comes in several formats — the 6800,
6809, FLEX, or even Radio Shack version on disk. The pro-
gram is fast and responds intelligently to simple sentences.

Minuses: Proper nouns must be capitalized for ESTHER to
recognize them.

Documentation: A detailed manual includes clear instruc-
tions for loading and running; some of the major subrou-
tines of the program are covered in detail. A little back-
ground on artificial intelligence programs is included.

Skill level required: None.

Reviewer: Bill Ball

Product Name: WP 6502 Version 1.3a

Equip, req'd: OSI Disk System

Price: $250 (65D)

$ 25 Upgrade from Version 1.3

Also available in 65U
Manufacturer: Dwo Quong Fok Lok Sow

548 Broadway

Suite 4F

New York, NY 10012
Description: WP 6502 is a full-feature word processor for
OSI computers. Text files are created and edited with the
TYPE, INSERT, DELETE, and REPLACE commands.
Sentences and paragraphs can be rearranged via the block
move utility. The global edit command allows all occur-
rences of "SMITH" to be replaced with "BROWN". Fixed
segments of texts can be called into the current file by typ-
ing four control characters. All disk operations are per-
formed by the file-clerk utility including LOAD, SAVE,
RENAME, ERASE, and DIRECTORY.

Pluses: Owners of earlier versions of WP 6502 can upgrade
to revision 1.3a at a small additional cost. The file clerk
utility includes a copy routine to initialize disks and make
backup copies of any text files or even WP 6502. A
memory test and disk test are included in the file clerk.

There is an INSTALL command, which allows WP 6502
to be custom configured to your needs. Options include
changing default parameters and assignments of control
characters, as well as accommodating differences in ter-
minal and printer character sets.

Minuses: Text files created by version 1.3 must be edited
before running on version 1.3a to reflect the changes in the
margin, tab, and line feed control characters. Editing is

MICRO

No. 57 ■ February 1983

Reviews in Brief (continued)

done on the unformatted text file. In this mode, control
characters are displayed but do not function and words
may be split between lines. The user must flip back to the
view mode to see the effect of his editing on the formatted
output.

Documentation: The program is supplied with an opera-
tion manual and a training manual. The training manual is
written for the non-computer user. The disk is supplied
with a number of text files already in place complete with
errors.

Skill level required: No computer knowledge necessary.

Reviewer: Earl D. Morris

Product Name: Touch Typing Tutor

Equip, req'd: VIC-20 (5K or more)

Price: $15.95

Manufacturer: Taylormade Software

8053 E. Avon Lane

Lincoln, NE 68505
Author: Marian Taylor

Description: The Touch Typing Tutoi package contains
two programs to teach the beginner how to type by touch
rather than by "hunt 'n peck." The first program,
LESSONS, is divided into 19 separate drills on the finger-
ing of keys, ranging in difficulty from the "home row" in
the first drill to punctuation in the last drill. The VIC
tracks your progress and shows your % correct for each
drill. The second program, PRACTICE, gives you random-
letter sequences and then measures your speed and ac-
curacy as you type in the sequences.

Pluses: Fun, useful, and well done! My kids (ages 9 and 10]
love it; they learned where all the keys are effectively and
enjoyably.

Minuses: Typing random letter sequences is not really a
good test of typing speed. Random sentences would be
more realistic.

Documentation: The 12-page manual is well written and
quite comprehensive.

Skill level required: None.

Reviewer: David Malmberg

VIC Adventure Cartridges

VIC-20 (5K or more)

$39.95 each

Commodore Business Machines, Inc.

487 Devon Park Drive

Wayne, PA 19087

Scott Adams

Description: Commodore has released the first five of
Scott Adams' classic Adventure games on cartridge for the
VIC-20. These are outstanding games that allow you to in-
dulge in fantasy role playing by giving your VIC simple
one- or two-word commands, like GO NORTH, EXAMINE

Product Name:
Equip, req'd:
Price:
Manufacturer:

Author:

}IIM's eating
your A[^le?

Find out with Apple-Cillin II

If you use your Apple for your business or
profession, you probably rely on it to save you
time and money You can't afford to guess
wfietfier it is working properly or not. Now you
don't fiave to guess. Now you can find out
witti Apple-Cillin II.

Apple-Cillin II is ttie comprefiensive diagnostic
system developed by XPS to check the
performance of your Apple II computer system.
Apple-Cillin II contains 21 menu driven utilities
including tests for RAM memory ROM
memory, Language Cards, Memory Cards,
DISK system. Drive Speed, Keyboard, Printer,
CPU, Peripherals, Tape Ports, Monitors and
more. These tests will thoroughly test the
operation of your Apple, and either identify a
specific problem area or give your system a
clean bill of health. You can even log the test
results to your printer for a permanent record.

Apple-Cillin II works with any 48K Apple system
equipped with one or more disk drives.

To order Apple-Cillin II - and to receive
information about our other products - Call
XPS Toil-Free: 1-800-233-7512. In Pennsylania:
1-717-243-5373.

Apple-Cillin II: $49.95. PA residents add 6%
State Sales Tax.

XPS

XPS, Inc.

323 York Ro3d

Cadisle. Pennsylvanis 1/013

800-233-7512

n/-243-53/3

Apple It is a registered trademarf( of Apple Computer Inc.

No. 57 - February 1983

MICRO

Vi--^

Let Unique Data Systems help you raise your sights on AIM 65
applications with our versatile family of AIM support products.

•Go for high quality with our ACE-100 Enclosure. It accom-
modates the AIM 65 perfectly, without modification, and features
easy access two board add-on space, plus a 3" x 5" x 1 7" and a
4" X 5" X 15.5" area for power supplies and other com-
ponents. $186.00.

• Get high capability with Unique Data System's add-on boards.
The UuS-1 00 Series Memory-l/0 boards add up to 1 6K bytes of
RAM memory or up to 48K bytes ROM/PROM/EPROM to your
Rocl<well AIM 65. You also get 20 independently programmable
parallel I/O lines with an additional user-dedicated 6522 VIA, two
independent RS-232 channels with 16 switch-selectable baud
rates (50 to 19.2K baud), and a large on-board prototyping area.
Prices start at $259.00.

• If you need to protect against RAM data loss, the UDS-100B of-
fers an on-board battery and charger/switchover circuit. $296.00.

• Heighten your AIM 65's communications range by adding the
UDS-200 Modem board. It features full compatibility with Bell
System 103 type modems and can be plugged directly into a
home telephone jack via a permissive mode DAA. No need for a
data jack or acoustic coupler. The UDS-200 also has software-
selectable Autoanswer and Autodial capability with dial tone
detector. The modem interfaces via the AIM 65 expansion bus,
with the on-board UART and baud rate generator eliminating the
need for an RS-232 channel. $278.00.

• The UDS-300 Wire Wrap board accepts all .300/.600/.900 IC
sockets from 8 to 64 pins. Its features include an intermeshed
power distribution system and dual 44-pin card edge connectors
for bus and I/O signal connections. $45.00.

• Get high performance with the ACE-100-07 compact 4" x 5" x
1 .7" switching power supply delivering -F 5V @ 6A, -H 2V @ 1 A,
and -F24V for the AIM printer. $1 18.00.

Installation kits and other related accessories are also avail-
able to implement your AIM expansion plans. Custom hard-
ware design, programming, and assembled systems are also
available. High quality, high capability, high performance, with
high reliability ... all from Unique Data Systems. Call or write
for additional information.

Unique Data Systems Inc.
1600 Miraloma Avenue, Placentia, CA 92670

(714)630-1430

Reviews in Brief (continued)

HOLE, JUMP, THROW AXE, etc. You can discover a
pirate's treasures, find and disarm a bomb before it blows
you up, or other daring exploits. These complicated and
time-consuming games are loads of fun for adventurers of
all ages. Games in progress may be saved on and loaded
from tape. For added excitement, use the Votrax Type 'N
Talk to run the first series of talking adventures.

Pluses: Great adventures creatively done! The cartridge
format is easy to use, and allows a 16K program to run
without any additional memory beyond the standard 5K.
The talking feature is fun if you are fortunate enough to
have a Votrax.

Minuses: These cartridges require you to LOOK (or "L"
for short) at your surroundings whenever you move to a
new location. This quickly becomes tedious. The docu-
mentation on the Votrax interface is wrong; it requires a
2400 baud rate rather than the 1200 rate claimed.

Documentation: Each of the five cartridges comes with
the same well- written 12-page manual that explains the
basics of adventuring, plus gives valuable hints for suc-
cessful play.

Skill level requited: None, other than imagination,
perseverance, and luck.

Reviewer: David Malmberg

Product Name:
Equip, req'd:

Price:
Manufacturer:

Author:

Story Machine

Apple n with Applesoft or Apple II

Plus with 48K RAM, DOS 3.3

$34.95

Spinnaker Software

215 First St.

Cambridge, MA 02142

(617) 868-4700

Design Ware
Copy Protection: Yes

Description: Story Machine is an educational program to
help children, ages 5 to 9, write sentences, paragraphs, and
simple stories. It develops vocabulary skills and keyboard
familiarity. You type in simple sentences and the program
acts them out in graphics .

Pluses: Story Machine is well written and interesting
enough to keep a young child occupied for hours on end in
writing short amusing stories. It is easy to use and has an in-
formative guide. The graphics are illustrative and well done.

Minuses: The dictionary is limited and exacting. Perfect
typing, not all that easy for a five-year-old, is required; no
unnecessary spaces are allowed. The child must also be
reading fairly well to run the program on his own.

Skill level required: Reading ability and interest in com-
puters. Five years old might be too young.

Reviewer: Phil Daley

iMCftO

100

MICRO

No. 57 - February 1983

iJMCftO

Software Catalog

Name: The DOS

Enhancet (TDE)

System: Apple II, DOS 3.3,

ROM/RAM card
Memory: 48K
Language: Machine Language
Hardware: Disk II
Description: The DOS En-
hancer (TDE) utility creates
copyable DOS 3.3 disks that
start up directly and quick-
load a RAM card in 1.8 sec-
onds. Its remarkable speed and
efficiency comes from fixing
all known "bugs," rewriting
DOS (including the file
manager) for enhanced speed
of operation and assembling
the resultant new TDE Quick
DOS. Compatibility with stan-
dard Apple DOS 3.3 programs
is maintained.
Price: $69.95
Includes utility disk,
training/ support disk, and
complete documentation.
Author: Art Schumer
Available:
S&H Software
58 Van Orden Road
Harrington Park, NJ 07640
(201) 768-3144

Name: Advanced

X-Tended Editot

System: Apple II, Apple II

Plus; DOS 3.3
Memory: 48K
Language: Applesoft
Description: The Advanced
X-Tended Editor (AXE) is a
professional programming aid
that provides the user with a
text editor-style extension to
the standard Applesoft oper-
ating system. AXE is called
upon by one of over thirty
commands that are easy, log-
ical, and operate in the normal
Applesoft entry mode or in
AXE's editing modes. AXE
operates on BASIC code as
stored in memory by Apple-
soft. No conversion of code to
text is required. In addition, all
Apple n DOS and monitor com-
mands are left fully functional.
Price: $69.95

Includes floppy diskette and

complete documentation.
Available:

Versa Computing, Inc.

3541 Old Conejo Rd.

Suite 104

Newbury Park, CA 91320

(805) 498-1956

Name: GiaFORTH
System: Apple II or Apple

nPlus
Memory: 48K
Language: Machine Language
Hardware: DOS 3.3 and one
or more disk
drives
Description: GiaFORTH is a
fast compiled graphics lan-
guage similar to FORTH, but
with many built-in graphics
features, including line and
area graphics, Turtlegraphics,
character graphics, and ani-
mated 3-D graphics.
Price: $75.00

Includes diskette and

220-page manual.
Author: Paul Lutus
Available:

Insoft, Inc.

10175 SW Barbui Blvd.

Suite 202B

Portland, OR 97219

Name: Semi Draw
System: TRS-80 Color

Computer or TDP
System 100
Memory: 32K
Language: Extended BASIC
Description: With Semi Draw
your computer's keyboard or
joystick draws in eight colors
with semi-alpha graphics 8, 12,
and 24. Semi Draw provides
animation and dumps the pic-
ture of the screen to a Line
Prmter Vn/Vni, NEC 8023, or
C. Itoh 8510 printer. Just press
the space bar to see the HELP
display for instructions. This
graphics program makes draw-
ing with the Color Computer
fun and easy for anyone six
years and older!
Price: $21.95 cassette only

Includes cassette and

instructions.
Author: Paul S. Hoffman
Available:

Computerware

P.O. Box 668

Encinitas, CA 92024

(714) 436-3512

Name: GrapfaPowei

System: Apple n, Apple III,

IBM PC, DEC
Memory: 64K
Language: Pascal
Hardware: Disk drive
Description: GraphPower pro-
duces V-ish-quality business

graphics at low cost. Using data
input from the keyboard or the
Micro-DSS/Finance finanacial
modeling system, GraphPower
creates camera-ready graphics
on paper or transparencies for
presentations and produces
graphs and charts including bar,
stacked bar, side-by-side bar,
line, pie, text, and reports.
Features include automatic or
manual scaling, eight letter
sizes with five slants, up to four
graphs per page, multiple image
overlays, unlimited shading
combinations, text annotation,
mathematical operations, 260
data points, and more.
Price: $295.00
Available:

Ferox Microsystems, Inc.

1701 N. Ft. Meyer Dr.

Arlington, VA 22209

(703) 841-0800

Name: Diversi-DOSTM

System: Apple n, Apple n

Plus
Memory: 48K
Language: Assembly
Hardware: 16K - 128K RAM

card optional
Description: Diversi-DOS is a
new Apple DOS 3.3-compati-
ble operating system that loads
and saves BASIC, binary, and
text files two-to-five times
faster than standard DOS 3.3.
Diversi-DOS also contains a
keyboard type-ahead buffer
and print-buffer utility. A sim-
ple, menu-driven, installation
program is included on the un-
protected disk.
Price: $30 by mail order only

Includes program disk and

documentation.
Author: Bill Basham
Available:

Diversified Software
Research, Inc.

5848 Crampton Ct.

Rockford, IL 61111

Name: Stellar Shuttle

System: Atari 400/800
Memory: 32K disk,

16K cassette
Language: Machine Language
Hardware: Joystick
Description: Assigned a dan-
gerous rescue mission to the
planet Ttam, you maneuver
your space shuttle from the
mother ship and begin a

perilous descent to the surface,
attempting to avoid streaking
asterpods along the way. Retro
rockets control your rate of
descent to the narrow landing
wells on the planet's surface
where hostages eagerly wait
for your arrival. The rockets
also provide your only defense
against pesky dragons that
have a taste for Ttamians and
will do their best to thwart
your attempt to rescue the
hostages and transport them
safely to the mother ship. Four
different levels of play are
available.
Price: $24.95
Author: Matt Rutter
Available:

Broderbund Software, Inc.

1938 Fourth Street

San Rafael, CA 94901

(4151 456-6424

Name: Veecee-Writer

System: Apple II Plus,

DOS 3.3
Memory: 48K
Language: Applesoft
Hardware: Disk drive
Description: Veecee-Writer
translates VisiCalc (/PF) files
for Apple Writer.
Price: $15.00

Includes instructions and

copyable program disk.
Available:

Bill Starbuck

2100 E. Edge wood

Shorewood, WI 53211

(414) 963-9750

Name: Ear Challenger

System: Apple II Plus
Memory: 48K
Language: BASIC
Hardware: One disk drive
Description: Instructional les-
son designed to teach elements
of music to children or adults.
Price: $39.95

Includes documentation and

diskette
Author: John M. Eddins and

Robert L. Weiss, Jr.
Available:

Electronic Courseware
Systems, Inc.

P.O. Box 2374, Station A

Champaign, IL 61820

(217) 359-7099

(Continued on next page)

No. 57- February 1983

MICRO

101

Software Catalog (continued)

Name:

System:

Memory:

Language:

Hardware:

Hi-Res Plotting
Package

Apple II Plus with
Applesoft ROM
(DOS 3.2 or 3.3)
48K

Applesoft
Disk drive, Epson
printer with
Graftrax |optional|
Description: Hi-Res Plotting
Package features hi-res func-
tion plotting with a twist.
Graphs are calculated and
stored on disk, then viewed in
rapid succession when the
game paddle is turned. This
package makes every Apple an
oscillosope. A 3-D plotter
(transparent and hidden line) is
included along with many
other useful math routines.
Price: $19.95
Includes floppy disk and
complete instructions.
Author: William C. Jones
Available:
Apex Software Co.
8781 Troy St.
Spring Valley, CA 92077
(619) 466-2200

Name: Colorcom/E

System: TRS-80 Color

Computer
Memory: 4K - 64K
Language: Machine Language
Hardware: ROMpak or

diskette
Description: The ColoTCom/E
is a smart terminal program
that comes in a ROM cartridge
ready to plug in and run.
Features and capabilities in-
clude on-line and off-line

scrolling, off-line printing of
data, receiving and sending
cassette files, and support of
any serial printer. Data can be
easily edited before printing or
writing to cassette or disk.
Price: $49.95

Includes manual.
Author: Mark Davidsaver

Available:

Spectrum

Projects

93-1586 Drive

Woodhaven, NY 11421

(212) 441-2807

Name:

Crossword

Scrambler

System:

Apple m

Memory:

128K

Language:

Tum-key system

Hardware:

Built-in disk drive

and 80-character

monitor
Description: Crossword Sciam-
blei is an educational software
product created to teach facts
and spelling on five different
subjects with graphically for-
matted screens and audio out-
put. User-friendly prompts are
designed for hands-on experi-
ence and computer interface.
Data security concepts and
password protection are dem-
onstrated within the programs.
Price: $39.95 ppd.

(20% discount to bona fide

educational institutions)

Includes diskette and

documentation.
Author: David Cortopassi
Available:

SOFPROTEX

P.O. Box 271

Belmont, CA 94002

Name: Micro Cookbook
and Micro
Barmate

System: Apple H, Apple H

Plus; DOS 3.3
Memory: 48K
Language: Compiled

Applesoft BASIC
and 6502
assembler
Description: Micro Cookbook
and Micio Barmate are
automated reference systems
that instantly provide food or
beverage recipes based on the
ingredients the user has on
hand. Drink and food recipes
are selected via three methods:
recipe name, category, and/or
available ingredients. They
also provide other food- and
drink-related information —
nutrition guides, calorie
counter, party planning, etc.
Both programs are fast and
simple to use.
Price: $30.00

Includes software, basic

recipe diskette, 28-page user

manual, recipe index, and

ingredient index.
Author: Joseph W. Butler III

and Brian Skiba
Available:

Virtual Combinatics

P.O. Box 755

Rockport, MA 01966

Name: Computer Slide
Express

System: Apple n Plus
Description: Apple Computer
owners can convert com-
puterized charts, designs,
graphs, and graphics to 35 mm
slides, prints, or overhead
transparencies. With our new
Compute! Slide Express, Apple

owners simply push a button
to dial Visual Horizons in
Rochester, transmit the infor-
mation over ordinary tele-
phone lines and receive by
mail 35 mm color slides, stan-
dard size black-and-white
prints, enlargements, or over-
head transparencies.
Price: $6.00 each,

$30.00 minimum
Available:

Visual Horizons

180 Metro Park

Rochester, NY 14623

(716) 424-5300

Name: Computer

Football Strategy

System: TRS-80 Models I
and III, IBM PC
Memory: 32K - TRS-80
64K - IBM PC
Language: BASIC
Hardware: One disk drive
Description: Computer ver-
sion of Avalon Hill's famous
board game is based on the
award-winning Sports Illus-
tiated game of professional
football. It forces the player to
constantly make the right
decisions about his team's of-
fensive and defensive forma-
tions. Match wits against the
computer or against a live
opponent.
Price: $21.00

Includes diskette.
Available:

Avalon Hill Microcomputer
Games

4517 Harford Road

Baltimore, MD 21214

iMCftO

,TM

IS THERE LIFE ARER BASIC ?

YES I WITH.

COLORFORTH

MOVE UP FROM BASIC! Forth is a new, high level language available now for the TRS-80® Color Com-
puter. COLORFORTH, a version of fig FORTH, has an execution time as much as lO to 20 times faster than
Basic, and can be programmed faster than Basic. COLORFORTH is highly modular which make testing
and debugging much simpler. COLORFORTH has been specially customized for the color computer and
requires only 16K. It does not require Extended Basic. When you purchase COLORFORTH, you receive
both cassette and RS/DISK versions, the standard fig EDITOR and an extensive instruction manual. Both
versions and 75 page manual $49.95

Add $2.00 shipping

DEALER AND AUTHOR INQUIRIES INVITED

Texas residents add 5 percent

ARMADILLO INT'L SOFTWARE
P. O. Box 7661
Austin, Texas 78712

MortwOvd

VKA

Phone (512) 459-7325

102

MICRO

No. 57 - February 1983

/MCftO

Hardware Catalog

Name: MiciomouseTM

System; Any
Description: The Miciomouse
is a small, hand-held device
that can be interfaced easily to
any microcomputer. When the
mouse is moved on a table top,
the cursor or pointer moves on
the computer screen. The
mouse has two butttons to
draw lines on the screen. The
buttons also can be used to
identify^ move, and position
symbols.
Price: $180.00 in single

quantities, $72.00 in

quantities above a thousand.

Includes instruction manual.

Available:
3G Company, Inc.
Rt. 3, Box 28A
Gaston, OR 97119
(503) 662-4492

Name: HypeicartridgeTM

System: Atari 400/800
Memory: 16K
Description: Hypeicaitiidge
gives hobbyists the ability to
make their own cartridges at
home. Software firms can
market extensive ROM-based
cartridges for use with 8K
RAM (or more) computers
without disk drives. It comes
with four low-profile sockets
for 24-pin ROMs or EPROMs
(chips not included), two pin-
select logic chips, and a
capacitor. Hypeicaitiidge can
be used in two configurations:
with any combination of 2532
EPROMs and 2332 ROMs; or
with two Atari ROMs and two
2532 EPROMs or 2332 ROMs.
Price: $39.00/unit; quantity
discounts available.
Includes configured cartridge
without EPROMs/ROMs

Available:
ChameleonTM Computing
Dept. of Physics and

Astronomy
Box 119-P
Dickinson College
Carlisle, PA 17013
(717) 245-1717

Name: Computet Practice
Keyboard

System: Any
Description: The printed key-
board is used to practice
special function-key locations

and to become familiar with
all popular computers.
Price: $9.95 each

Includes shipping and

handling.
Available:

Computer Practice Keyboard
Company

616 9th St.

Union City, NJ 07087

Name: Ink Stick
Description: Ink Stick mounts
inside most spool ribbon-
dependent printers that use
Vi ' ' spool ribbons and immedi-
ately replaces ink that is
depleted from the ribbon to
maintain an appropriate level
of ink in the ribbon at all
times. This extends the life of
the ribbon frabic, reduces the
operating cost of the printer,
provides the user with consis-
tent image density, and
reduces the number of times
ribbons are handled.
Price: $4.95 retail
Includes mounting cap,
%-oz. ink in container,
applicator wick, and
installation instructions.
Available:
Lawrence Electronics
3651 N. Cicero Avenue
Chicago, IL 60641

Name: Sage n

System: Sage II
Language: Pascal, FORTRAN,
BASIC, Assembler
Description: Sage II offers the
highest performance-per-dollar
computer on the market in the
price range of the IBM/ Apple
ni, but with four to twenty
times more computing power.
Expansion capability includes
more RAM, multi-user multi-
tasking, hard drives, networks,
and graphics.

Price: $4,450.00
Includes 128K RAM, 320K
floppy, televideo 925 term,
software

Available:
Sage Computer Technology
35 N. Edison Way, Suite 4
Reno, NV 89502

Name: Data VaultTM

Description: Date Vault pro-
tects your computer tapes.

disk cartridges, and floppy
disks from the hazards of ship-
ping and storage. They feature
a rugged polyethylene exterior,
internal shock-absorbing
foam, and a positive-action
locking, system. Send for a
catalog.
Available:

Kathy Sutherland

Sales Manager

Data Vault Division at

PRC of America

475 Boulevard

Elmwood Park, NJ 07406

(201) 796-6600

Name: ITALKII Speech
Synthesizei

System: Atari 400/800
Memory: 16K
Language: BASIC
Description: ITALKII offers an
unlimited vocabulary, four
voices, and powerful program
development utilities. It re-
quires no external power sup-
ply and outputs speech to the
monitor's speaker. A machine-
language driver allows ITALKII
to speak while action graphics
and sound effects are being ex-
ecuted. Software includes a
dictionary, a word editor, a
sentence builder, and Woid-
blastei (an arcade-style educa-
tional game).
Price; $199.00
Includes ITALKII, disk or
cassette, manual, phonetic
speech dictionary.

Available:
Greenbrier Marketing
International, Inc.
509 South 48th St.
Suite 105
Tempe, AZ 85281
(602) 948-0005

Name: Starfighter,

The Ultimate
Joystick

System: Atari VCS, Atari
400/800,
Commodore VIC,
Sears Tele-Game
Description: This joystick con-
troller is designed with an ad-
vanced mechanism that trans-
fers movement directly from
the user's hand through case-
hardened steel components to

the internal contacts. Its
rounded shape helps to elimin-
ate muscle fatigue when using
other joysticks for long peri-
ods. Controller carries a two-
year limited factory warranty.
Price: $16.95
Available:

SUNCOM, Inc.

270 Holbrook Dr.

Wheeling, IL 60090

Name: Color HI
System: TRS-80 Color

Computer
Memory: 4K - 64K
Description: If you are a do-it-
yourselfer then you can
upgrade a color computer to a
65-key keyboard with numeric
pad, integrated television and
computer display screen,
telescopic antenna, internal
disk and sound, channel selec-
tor knob, indicator lamps,
ROM pack slot, and all I/O
connector jacks mounted in a
Model III enclosure. Color
Computer products work as
before.
Price: $15.00

Includes instruction manual,

12 professional drawings and

templates, bill of material,

check-off list, and

manufacturing list.
Available:

L & E Electro Sales Co.

7017 Hazehine Ave #10

Van Nuys, CA 91405

(213) 994-3110

Name: Joypoit

System: Apple n or Apple

nPlus
Description: Joypoit expands
the game port to use four fully
functional Apple-compatible
paddles and two Atari-type
joysticks. No modification is
necessary. The Joyport simply
plugs into the existing game
I/O port.

Price: $49.95
Includes user's manual.

Available:
Sirius Software
10364 Rockingham Drive
Sacramento, CA 95827

JMCftO

No. 57 - February 1983

MICRO

103

JMCRO

6809 Bibliography

Dr. William R. Dial
438 Roslyn Avenue
Akron, OH 44320

101. 80 Micro (October, 1982J

Miller, Franklyn D., "The Colorful Computer — Part III," pg.

254-260.
A number of program listings for those without Extended
Color BASIC in their TRS-80 Color Computer.

Degler, Roger L., "LP VII Patch for the CO," pg. 304-306.
An eight-bit printer-driver for the 6809-based Color Computer.

102. Popular Electionics 20, No. 10 (October, 1982J

Anon., "6809 FORTRAN," pg. 42.
Running under FLEX and UniFLEX, this compiler complies
with ANSI FORTRAN-77 subset of FORTRAN.

103. Call — A.P.P.L.E. 5, No. 9 (September, 1982J

Anon., "Enhancement to The Mill," pg. 75.
MSM is an enhancement to The Mill Assembler Develop-
ment Kit that combines the features of ASM09,
ASM09IO.BIN and LOAD09. Thus, a stand-alone MSM09
BRUNable 6809 assembler.

104. Personal Computer World 5, No. 9 (September, 1982)

Anon., "Dragon 32," pg. 40-41.
The Dragon 32 is a 6809-based personal computer, 32K RAM,
nine colors, high-resolution graphics, etc.

105. Commodoie Microcomputer Magazine 3, No. 4 (August/
September, 1982)

Kutz, Walt, "SuperPET Update," pg. 14.
COBOL for the 6809-based SuperPET, using extra memory,
single board upgrade (8032 to SuperPET), accessing the serial
port, etc.

Staff, "Commodore News," pg. 21.
Everything you always wanted to know about the 6809-based
SuperPET — and asked! Questions and answers.

106. The Rainbow 2, No. 3 (September, 1982)

Lester, Lane P., "An Electronic Gradebook Can Make '82-'83
Much Easier," pg. 8-14.

A program for the TRS-80 Color Computer-equipped teacher.
Walrath, Del, "Let's Learn How To Do a Number-Picking
Game," pg. 18-20.

A programming tutorial using a number-memory game.
Nolan, Bill, "Demons in the Dungeon? Let's See 'Em All," pg.
22-32.

A program to get quick information about a particular kind of

demon without looking it up. A TRS-80 Color Computer

dungeon game utility.

Harpe, David, "PUT, GET and Random Forms Make for
Unusual Graphics," pg. 32-33.

A graphics program for the 6809-based Color Computer.
Blyn, Steve, "Make the Difficulty Level Variable," pg. 35-36.

Suggestions and an illustrative listing for CAI programs on

the 6809-based TRS-80 Color Computer.
Hryzak, Wolfgang, "Ping-Pong International Game for People
and 80C," pg. 41-43.

A German game for the 6809-basd Color Computer.
Roslund, Charles J., "An Automatic Key Repeat Feature is
Handy to Have," pg. 47-49.

Add auto-key repeat to your Color Computer with this

machine-language routine.
Schmidt, Jim, "Here Are Some Useful Utilities for Your Use,"
pg. 51-53.

Utilities for the Color Computer include a line-width driver,

an 8-bit graphics driver, and a speed routine.

Rosen, Bob, "The Simple Way to 64K," pg. 59.

A hardware modification to convert the 6809-based Color

Computer to 64K.
Hine, Al, "The Track Will Provide Hours of Varied Fun," pg.
60-70.

A race game for the 6809-based Color Computer.

107. 80-U.S. Journal 5, No. 10 (October, 1982)

Beste, Steve Den, "Word Processing on Your Color
Computer," pg. 65-74.

A line-oriented text editor for the TRS-80 Color Computer

with disk.
Fawcett, Dale H., "Serial Printer Interfacing," pg. 95-97.

Coimecting to your 6809-based Color Computer.

108. MICRO No. 58 (October, 1982)

Whiteside, Tom, "Apple Pascal P-Code Interpreter and the

6809," pg. 79-84.
A rewrite of the Apple UCSD Pascal P-Code interpreter for
the MC6809 shows code size and speed improvements.

Tenny, Ralph, "A Homespun 32K Color Computer," pg. 91-95.
A hardware article detailing a relatively simple memory ex-
pansion from 16K to 32K in the Color Computer.

109. Microcomputer Printout 3, No. 11 (October, 1982)

Preston, Chris, "MicroScope," pg. 20-21.
Multiple processors and how they work including 6502/Z80,
6502/6809, and similar combinations.

110. Compute! 4, No. 10 (October, 1982)

Anon., "TRS-80 Color Computer Program," pg. 223.
Colortext for the 6809-based TRS-80 Color Computer is a
high-resolution text driver that displays a variety of character
fonts and graphics on the screen simultaneously.

111. Personal Computer 5, No. 10 (October, 1982)

Oliver, Roger and Sadler, Chris, "Positron 9000," pg. 128-134.
The Positron is a new British-made microcomputer using
6809 with 64K RAM.

112. '68 Micro Journal 4, Issue 10 (October, 1982)

Ney, Robert L., "Color User Notes," pg. 11-13.

Discussion of F-MATE Version 2.0, powerful business

systems for the TRS-80 Color Computer, etc.
Commo, Norm, " 'C User Notes," pg. 14-19.

Discussion of Intersoft Version 1.0, a small C compiler for

the 6809.
Watson, Ernest Steve and Brady, F. Dale, "Home Accounting
Program," pg. 20-23.

Part in of an accounting system for 6809 systems.

113. The Rainbow 2, No. 4 (October, 1982)

Ridge, Herbert B., "Pope Gregory Would Like This Calendar,"
pg. 8-12.

A calendar program for the TRS-80 Color Computer.
Inman, Don, "Let's Learn How to Use Graphics with CoCo,"
pg. 14-17.

A graphics tutorial for the 6809-based Color Computer.
Garrett, Ron, "Key Checks to Various Accounts with This Pro-
gram," pg. 20-24.
A Color Computer program to allow you to designate spend-
ing areas for a check or payment into different categories for
business expenses. _

JMCftO

104

MICRO

No. 57 - February 1883

Language Packages

Editor's Note: This list of Language Packages is
not meant to be comprehensive.

Ada

^^H

68000

Ada Compiler

TeleSoft

q-Bus, Multi-bus, S-100 configurations

$250

^^H

Z80, 8080,

Ada

Supeisoft

CP/M, MSDOS, 32K RAM min.

$350

^^^H

8086, 8088

^^^1

APL

^^M

Apn

APL

Vanguard

Z80 softcard, RAMcard, 1 drive, 48K

$500

^^M

BABBLE

Ap n

BABBLE

Software Factory

16K cass/32K disk

$15 Icass)

CEEMAC

$20 (disk) 1
1

J g

)QfQ

Ap n/n

CEEMAC

Vagabondo

48K

$75 1

COBOL

Ap n/n Plus

COBOL-30

Microsoft

2 drives/44K/Softcard

$750

Enterprises

OSI

COBOL

Prism Software

6809, 68000

RM/COBOL

Ryan-McFarland

Unix(68000], 8 disk, 1 drive, 64K (6809)

$750 - §• ^
$1250 S, fP

$600 03 13

Data Compass
Corp.
OSI

OSIC-3

COBOL 3.3

CP/M

Ap n/n Plus

Nevada COBOL

EUis Computing

Softcard, CP/M, 1 drive

$29.95 -■ fti

$850 o jr

$29.95 ^ LL

<D org

; «
3 en

6502

CIS COBOL

MicroFocus

UNIX or CP/M

Apn/n

Nevada COBOL

FORTH, Inc.

Softcard, CP/M, 1 drive

COMAL-80

PET

COMAL-80 [best

Metanic

CP/M

of BASIC &

Pascal)

FOCAL-65

ApD,SYM,

Fast FOCAL-65

6502 Program Bxchange

48K, 1 drive (Apple), 16K, cassette (others)

AIM, OSI, KIM

j^^^

FOUO

KIM-1
FORTE

FOLIO

Soft Corp

$50

cass $3 extra

Apn

FORTE

SofTape

$29.95

w/Intener

^^H

FORTH

^^M

Ap n/n Plus

TransFORTH n

Insoft, Inc.

1 or more disk drives/48K/DOS 3.3

$125

^^H

fig-FORTH

Atari

lOK

^^^1

Ap n/n Plus

FORTH
(Microspeed,
superset of
FORTH)

Applied Analytics, Inc.

4KRAM

$495 (2 MH2)
-u Speed E
$645 (4 MHz)
-u Speed H Plus

■

SuperFORTH

Hayden Software

48K/DOS 3.2

$49:95 disk

^^^H

TRS-80C

CC FORTH

Frank Hogg

Disk drive

$99.95

^^^H

Apn/n

FORTH 72
Version 2

MicroMotion

1 disk drive

$89.95/
$139.95 hi-res
& floating point

6809

FORTH 6809

Talbot Microsystems

$100

^^^H

SYM-1

SYM-FORTH 1,0

Saturn

$135

^^^H

6502

fullFORTH

CGRS Microtech

$65

^^^H

Apn/n

FORTH-79

MicroMotion

1-6 disk drives, 48K, 80 column bd. optional

$99.95/

$139.95 with
•' floating point

& hi-res

■

OSI

Stand-Alone
fig-FORTH

FORTH Tools

$49.95

68000

PolyFORTH

$5100-8200

^^^H

6809

X-FORTH

Frank Hogg

FLEX, disk drive

$129.95

^^^H

COM-64

C64 FORTH

Performance Micro
Products

$79.95 cass/
$99.95 disk

VIC-20

VIC FORTH

HES

$59.95

^^^H

Ap n/n Plus

FORTH 1.7

Information Unlimited

1 disk drive, 48K, Ap DOS 3.2

$140

^^^H

FORTH I, n

SofTape

1 drive

$49.95

^^^H

OSI-C3, 4,

S-FORTH

Aurora

20K

$34.95 (OS65

^^^H

OS65D-3

D-3(, $49.95
with source
listing

Apn/n

GraFORTH

Insoft, Inc.

48K, 16K RAM card recommended, DOS 3.3, 1 drive

$75

^^^H

PET

FORTH

AB Computers

16K or 32K, PET/CBM disk drive

$50

^^^H

Apn/n

Timin FORTH 3.5

Lifeboat Assoc.

Z-80 Softcard, CP/M or CDOS, 32K min., 2 drives

$250

^^^H

TRS-80C

Color-FORTH

ArmadiUo Int'l.
Software

16K

$49.95

KIM

FORTH

Eric C. Rehnke

$90 cass/$7S
source code
only

$109.95

TRS-80C

Color-FORTH

MicroWoiks, Inc.

Language Packages will be continued in next month's issue.

JUCRO" Information Sheet #1

Language Packages

Addresses

AB Computers

252 Bethlehem Pike

Colmar, PA 18915

215-822-7727
Abacus Software

PO Box 7211

Grand Rapids, MI 49510

616-241-5510
Addison Wesley
Publishing Co.

Jacobs Way

Reading, MA 01867

617-944-3700
Apple Computer, Inc.

Software Division

10260 Bandley Drive

Cupertino, CA 95014

516-751-5139
Applied Analytics, Inc.

8235 Penn Randall Place,
Suite 202

Upper Marlboro, MD
20972

301-420-0700
Armadillo International
Software

PO Box 7661

Austin, TX 78712

512-459-7325
ATARI Home Computers

1265 Bonegas Ave.

Sunnyvale, CA 94086

800-538-8543
408-745-2100
Aurora Software Assoc.

378. Mitchell

Arlington, IL 6005

312-259-3150
CCRS Microtech

PO Box 102

Langhome, PA 19047

215-757-0284
Commodore Business
Machines, Inc.

681 Moore Rd.

King of Prussia, PA 19406

215-6987-9750
Compu/Think

965 West Maude Avenue

Sunnyvale, CA 94025

408-245-4033
Computerware

PO Box 668

Encinitas, CA 92024

619-436-3512
Creative Solutions

4801 Randolph Rd.

Rockville, MD 20852

301-9844-0262
Datasoft, Inc.

19519 Business Center
Drive

Northridge, CA 91324

213-701-5161
Duggers Crowing Systems

POB 305

Solano Beach, CA 92075
Dynasoft Systems, LTD

P.O. Box 51

Windsor Junction

Nova Scotia, CANADA
BON 2V0

902-861-2202

Ellis Computing

3917 Noriega Ave,

San Francisco, CA 94122

415-753-0186
Eric C. Rehnke Technical
Services

1067 Jadestone Lane

Corona, CA 91720

714-371-4548
FORTH, Inc.

2309 Pacific Coast
Highway

Hermosa Beach, CA 90254

213-372-8493
FORTH Interest Croup

POB 1105

San Carlos, CA 94070

415-962-8653
Frank Hogg Laboratory

130 Midown Plaza

Syracuse, NY 13210

315-474-7856
Gnosis

4005 Chestnut St.

Philadelphia, PA 19104

215-387-1500
Hoyt Steams Electronics

413E Cannon Dr.

Phoenix, AZ 85036
Human Engineered Software

71 Park Lane

Brisbane, CA 94005

415-468-4116
Information Unlimited
Software, Inc.

281 Arlington Ave.

Berkeley, CA 94707

415-525-9452
Insoft, Inc.

10175 S.W. Barbur Blvd.

Suite 202B

Portland, OR 97219

503-244-4181
JRT Systems

1891 23rd. Avenue

San Francisco, CA 94122

415-566-5100
Kenyon Microsystems

3350 Walnut Bend

Houston, TX 77042

713-978-6933
Keyser Enterprises

22 Clover Lane

Mason City, lA 50401
Krell Software

21 Millbrook Dr.

Stony Brook, NY 11790

516-751-5139
Lifeboat Associates

1651 Third Ave.

New York City,NY 10028

212-860-0300
Lucidata

POB 128

Cambridge CB2 5EZ

England
Merrimack Systems

PO Box 5218

Redwood City, CA 94063
Metanic ApS

Kongevejen 177

DK-2830

Virium, Denmark

Micro Focus, Inc.

1601 Civic Center Drive

Santa Clara, CA 95050

408-496-0176
Micro Motion

12077 Wilshire Blvd. 506

Los Angeles, CA 90025

213-821-4340
Micronetics Design Corp.

932 Hungerford Dr.,
Bldg. 11

Rockville, MD 20850

301-424-4870
Microsoft

400-108th Ave. NE

Bellevue, WA 98004

206-828-8080
MicroWorks

POBox 1110

Del Mar, CA 92014

619-942-2400
Muse Software

347 N. Charles Street

Baltimore, MD 21201

301-659-7212
Omega Software

POB 70265

Sunnyvale, CA 94086

408-733-6979
On-Going Ideas

RDl, Box 810

Starksboro, VT 05487

312-259-3150
On-Line

37575 Mudge Ranch Rd.

Coarsegold, CA 93614
Ohio Scientific Instruments

7 Oak Park

Bedford, MA 01730

617-275-4440
Prism Software

PO Box 928

College Park, MD 20740
Quality Software

6660 Reseda Blvd.,
Suite 105

Reseda, CA 91335

213-344-6599
Querty Computer Systems

20 Worcester Rd.

Newton Hall, Durham

England LI.25 67045
Radcliffe House

66-68 Hagley Rd.

Edgbaston, Birmingham

United Kingdom B16 8PF
Radio Shack Educational
Software Division

400 Atrium,
One Tandy Center

Fort Worth, TX 76102

817-390-3302
Ryan-McFarland Data
Compass Corp.

3233 Valencia Ave.

Aptos, CA 95003

408-662-2522
Saturn Software Limited

8246 116A Street

Delta, British Columbia

CANADA V4C 5Y9

6502 Program Exchange

2920 W. Moana

Reno, NV 89509

702-825-8413
Softcorp

1372 East 52nd. St.

Chicago, IL 60615
SofTape Software Exchange

10432 Burbank Blvd.

North Hollywood,
CA 91801

213-885-5763
SofTech Microsystems, Inc.

16885 West Bernardo Dr.

San Diego, CA 92127

714-942-1727
Software Factory

PO Box 904

Chatsworth, CA 91311
Sorcim

1333 Lawrence Expess-
way. Suite 148

Santa Clara, CA 95051

408-727-7634
Succinct Systems

1346 River St.

Santa Cruz, CA 95060

408-426-4197
SuperSoft

PO Box 1628

Champaign, IL 61820

217-359-2112
Tallgrass Technologies Corp.

9009 W. 95th St.

Overland Park, KS 66212

913-381-5588
Tamarack

Water St.

Darby, MT 59829

406-821-4596
Telesoft

10639 Roselle St.

San Diego, CA

714-457-2700
Tenapin, Inc.

678 Mass. Ave., 205

Cambridge, MA 02139

617-492-8816
Vagabondo Enterprises

1300E. Algonquin-35

Shawnburg, IL 60195

312-397-8705
valFORTH International

3801 E. 34th St.

Tucson, AZ 85713

800-528-7070
Vanguard Systems, Corp.

6901 Blanko

San Antonio, TX 78216

512-340-1978
Volition Systems

POB 1236

Del Mar, CA 92014

619-481-2286
Williamsville Publishing Co.

Box 250

Fredonia, NY 14063
Wordsworth

PO 28954

Dallas, TX 75228

214-783-0419

JUGRO" Information Sheet #1

NIBBLE EXPRESS Vol. I

TABU OF CONTENTS

EDITORIAL

APPLE TRAC — Personal Finance Management by Mike i
SORT 'EM OUT — Principles of Sorting by NIBBLE Staff
PSEUDO UTO-START — Reset with CTRL Y by Rick Con
INITIALIZE NEW FILES WITH ONERR GOTO by NIBBLE
MACHINE LANGUAGE SCREEN DUMP by R.M. Mottola

FREE? DISK SECTORS by Chuck Hartley ..... . . . .

HI-RES SPACE MAZE — Graphics Game by NIBBLE Staf:
UN-GRAPHIC GRAPHIC PRINTING by NIBBLE Staff . . .
TABLE PRINTING MADE SIMPLE! by A//ee/.E Staff .....
DYNAMIC ARRAY DIMENSIONING by NIBBLE Staff ....

BLOCKING VERY LARGE FILES by NIBBLE Staff

LOW RESOLUTION SHAPEWRITER — High Speed Actio
SPACE ANIMATION — Add ZIP to your Games by NIBBL
STAR ATTACK — Fast Hi-Res Conflict Game by Mike Hai
PADDLE READING IN ASSEMBLY LANGUAGE/)/ W/eSi
FIRINO^I^iS ja^'Ji^ ^irgrMiMli Control by NIBt
AIRSlQJEB-f-jJntl^mwprprce Maneuvers b
AUT(^^^^m^^\§fb§^^U0by NIBBLE Staff
WATCH OUT FOR GRAPHICS OVERFLOW by Mike Harv

TOUAkfmt^tiWMEmEtMmi^Mimtlleynolds til
TOU(irFllDmil#talL/i|:El>lrimV^Wam Reyno.
DOU BL&TRIPLEy'AWP MOWC OVgB P WIN T IWG by NIBBL

ARROWS AND CONTROL CODES by NIBBLE Staff

APPLE TRICKS — Fast DOS/Spcl Chars/Unlistables toy C
APPLESOFT VS. INTEGER BASIC PERFORMANCE by /*.
APPL^^ Paoer Tiger Graohics by Mike Harvey .......

FAST ipaaji^SXINfi AND SALES TRENDING by Mike h
SUPEm^Ki^^F^MM^es Weaving Design by Alexandei
FOOTB^I.^^oll»Grid-lron Action by Lou Haehn . .
BUILJdOAOSY^ICKS FOR UNDER $15.00 by NIBBL
BUILEUUKBUq^i^E^A^IiaaL IMITgi- MBBLE Staf

DISK W^mimmTi%^amMcgmfmmm nibble

PIP II I- Pll UteB CKccltlM^andli^.l

PASsliaWflMBLls ■ |pmA|Mlr%riRlC byR.M. Mt
MANAGING AND MOVING DISK BUFFERS by William Ri
MONITOR EXECUTION — Basically by William Reynolds
AMPER-INTERPRETER — Add Print-Using and Much Mo
FUN WITH ASSEMBLER — Graphics by Alexander Laird
STRING FUNCTION FOR INTEGER BASIC by William Re
BASIC/MACHINE LANGUAGE SUBROUTINE CREATOR
CHR$ FUNCTION FOR INTEGER BASIC byWiftiamReyn
FUN WITH ASSEMBLER — Alpha/Beeper by Craig Cross
APPLE A.I.M. — Automated Intelligent Mailing by W/cAaei
APPLE CONCORDANCE — Track Variable and Line #'s b

LOW SCORE II — Strategy Game by Rudy A. Guy

HOW TO WRITE GAMES THAT LAST by Mike Harvey . . .
IMPROVING THE MULTIPLE ARRAY SORT by fl/c/f Com
APPLE UPPER/LOWER CASE PRINTING by Mike Harvey
WILL O' THE WISP — High Adventure by Mark Capella . .
NIFFUM — DOS 3.3 to 3.2 Conversion by C.J. Thompson
BLAST AWAY! — Lo-Res Shooting Gallery by Andrew Be.
FUN WITH MONITOR — How to Enter Assembly Languac,

nibble

ORDER NOW

All programs and Articles are
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family.

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Page

3
7

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106

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174

If you're looking for quality software at an
outrageously reasonable price, we have
a message for you...

Apple^*^ owners:

10 HOME: P$ = "GZPV UREV WLOOZIH LUU HLUGHRWV":VTAB12:
HTAB6: FOR P = 1 TO LEN(P$):J » ASqMID$<P$,P,1)):PRINT
CHR$<ABS<(155*(J >64))-J));: NEXT:PRINT

TRS-80'owners:

10 CLS: DEFINT A-Z: PRINT@529,;: P$ = "GZPV UREV WLOOZIH
LUU HLUGHRWV": FOR P = 1 TO LEN(P$):J = ASqMID$<P$,P,1)):
PRINT CHR$<ABS<(155*(J>64)) + J));: NEXT:PRINT

ATARr owners:

10 GRAPHICS 0:DIM P$(30):P$ = "GZPV<UREV<
WLOOZIH<LUU<HLUGHRWV":FOR P = 1 TO 30:
?CHR$<155-ASqP$(P)));: NEXT P:?

ype

7>)>

Take a close look at the message above. If you own an
APPLE™, an ATARI®, or a TRS-80* microcomputer, you
probably rejbognlze the language.

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ilMOK)' Data Sheet #13

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iMCftO" Data Sheet #13

NATIONAL

ADVERTISING

REPRESENTATIVES

WEST COAST

The R.W. Walker Co., Inc.

Gordon Carnie

2716 Ocean Park Boulevard

Suite 1010

Santa Monica, California 90405

(213) 450-9001

serving: Washington, Oregon, Idaho, Montana, Wyom-
ing, Colorado, New Mexico, Arizona, Utah, Nevada,
California, Alaska, and Hawaii (also British Columbia
and Alberta, Canada).

MID-WEST TERRITORY

Thomas Knorr & Associates
Thomas H. Knorr, Jr.

333 N. Michigan Avenue

Suite 707

Chicago, Illinois 60601

(312)726-2633

serving: Ohio, Oklahoma, Arkansas, Texas, North
Dakota, South Dakota, Nebraska, Kansas, Missouri,
Indiana, Illinois, Iowa, Michigan, Wisconsin, and
Minnesota.

MIDDLE ATLANTIC AND
SOUTHEASTERN STATES

Advertiser's Index

Dick Busch Inc.
Richard V. Busch

6 Douglass Dr., R.D. #4
Princeton, NJ 08540
(201) 329-2424

Dick Busch, Inc.
Eleanor M. Angone

74 Brookline

E. Atlantic Beach, NY 11561

(516) 432-1955

serving: New York, Pennsylvania, New Jersey, Dela-
ware, Maryland, West Virginia, Virginia, D.C., North
Carolina, South Carolina, Loulsianna, Tennessee, Mis-
sissippi, Alabama, Georgia, and Florida.

NEW ENGLAND

Kevin B. Rushaiko

Peterboro, New Hampshire 03458
(603) 547-2970

serving: Maine, New Hampshire, Vermont, Massachu-
setts, Rhode Island, Connecticut, and Kentucky.

ADVERTISING MANAGER

Cathi Bland

address materials directly to:
MICRO INK, Advertising
34 Chelmsford Street
Chelmsford, Massachusetts 01824
(617)256-5515

Aardvark Technical Services, Ltd 39

ABC Data Products. 24

Acorn Software Systems 84

Alternative Energy Products 84

Anthro-Digital Software 18

Armidiilo Software 102

A2 Devices , .63

Aurora Software 27

Chameleon Computing 53

Commander Micro Systems Specialties 20

Compu Sense 14,16,49,79,93

CompuTech 70

Computer Case Co 91

Computer Mail Order 56-57

Computer Science Engineering 24

Datamost, Inc IPC, 77

Digital Acoustics 61

Execom, Inc . . . 70

Gimix, Inc 1

Gloucester Computer Bus Co 79

Gnosis 64

Gooth Software . . 15

Hayden Software 4

Human Systems Dynamic 76

Huntington Computing 94

Intec Peripherals Corp 25

Interesting Software 9

John Bell Engineering 21

L Com 55

Leading Edge BC

Logical Devices 20

Lyco Computing 52

Nibble 107

Manx Software 76

MlCRObits (Classifieds) 88,93

Microcomputing 32

MICRO INK 15. 45

Micro Motion

Micro Signal

Micro-Ware Distributing, Inc..

Modular Mining Systems

Modular Systems

Performance Micro Products.

Perry Peripherals

Privac

RC Electronics

RH Electronics

Scientific Software

SGC

...59

. 93
. . 68

. .87
...25

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. 42
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.6,80
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..46

SJB Distributors 30

Skyles Electric Works 8

Smartware .97

Softronics -2

Softside Publications 108

Sorrento Valley Assoc 36

Talbot Microsystems 59

Unique Data 100

Versa Computing 10

Vista Computing IBC

XPS, Inc 99

Zytrex 50

MICRO INK is not responsible for claims made by its adver-
tisers. Any complaint should be submitted directly to the
advertiser. Please also send written notification to MICRO.

No. 57 - February 1983

MICRO

111

Next Month in MICRO

New Section for the Serious Novice!

Developing Computer Literacy — Appearing
monthly in MICRO; basics for honne and for school,
in easy-to-understand ternns. Learn how to develop
connputer literacy using the VIC-20, Connnnodore 64,
Atari 400, TRS-80 CC, TI-99, Sinclair Tinnex, as well
as the Apple, PET, or Atari 800. Look for

MICROCalc for VIC and all Connnnodore connputers,
Apple, and CC — a worksheet progrann to define
and perfornn calculations.

DIGI-DRAFT — An Atari graphics progrann for
drawing images on the screen to save on tape or
disk for retrieval later.

BANNER: A Display Program for the CC — The
scrolling screen displays any message of your
choice.

The Computer Revolution — A look at the public's
response to computers.

March: Printer Feature

MULTIC — Multic Column Print for the AIM

A Full Byte for Your Apple Printer

PRINT- USING on the Apple

Plotting with the VIC

Disk ID for OSI Printed Directories

Plus:

A Versatile Hi-Res Graphics Routine for the Apple
Animated Graphics on the 6809
Single Floppy Disk Interface for 6502

20% OFF

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When You Subscribe

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a copy).

Special Offer — Subscribe for 2 years ($42.00)
and get 30% off the single issue price.

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112

MICRO

No. 57 ■ February 1983

GREAT INNOVATORS*

15th century renaissance man, Leonardo Da Vinci, con-
tributed an inexhaustible collection of inventions and ideas
to solve the world's problems. These ideas were centuries
ahead of their time. The studies on this page deal with ex-
periments in manned flight.

Like Leonardo, Vista Computer is answering many of
today's complex computer storage problems. The Vista
V1200 is a great solution to Apple II™ storage. Mass storage
for your Apple IF" Computer has always been a problem. On
one hand, there were the exotic, expensive hard disks with
no cost efficient means of backup. On the other hand, the
Apple floppy drive lacked the speied and storage demanded
by today's professionals.

Vista's V1200 offers both at an incredibly attractive price.
The removable VistaPak cartridges offer 6 Megebytes of
removable storage each and can be backed up like a floppy.

now hard disk storage and speed can be yours with the added
capability of interchangeable media. The V 1200 eliminates

the worries of head crashes, drive alignments, lost data, or
backup with a, new application of field-proven floppy
technology.

The VistaPak cartridges hold 6MB of formattedfdata each.
The removable cartridge allows you to keep duplicates of
your valuable data as well as to keep separate paks i$3X your,
accounting, word processinO/ spread sheet and other aoplh'
cations, rio other storage device oftcrb nioiu in flexibility
and capability. . - ]

• Micropiocoisur cuiilrolled diivc • DMA Controller *
Removable Data Cartridges • CPT^eil. DOS Ar Piibcal compati-
ble •' Qukkchargc^^, DOSeiihancemcTitinLluded • iiuJudcii
. 1 VistaPiak cartridge • Vista I ,i{» Day Wairanty *,"?*'

' ' ' **.

. Contact Your Local Vfsta Dealer or Call our VIsta/lotlines.

■^' , COMfiiTER """ • i?\
jWBE'COM'P/SNYiNcfej /■

1^17 East Edin^r ^$^nLft AriA CA 9276a-->'«*)- - > <.,
47 141 953-0523 '/ C8Qpf|S^-8()r7 . .,. f-;'?^' ■"

'Z *PP'^ " is a registered trademark of Apple Computer Co.

- DISTRIBUTORS"/

Wrsh-iii Cir iiip3*hnlt«lr ,'* '• *-
1.IM9JTB4* i1(N)t73^
- Stiiith lintiil 1 K SyiiPitiT

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I307 . ■**:_ji5*' , f •■■eJls"47hJ*<i\ 9iAs,l^r '
. ■■ ***^ " ■ - •I-*-* i' '-n •• aSEnSe, ■"•

i.-

", -.-s-jp,: ■

^•.^^^''^-•^'■'^^mH.

THE PROWRITER GOMEIH

(And It Cometh On Like CangbustersJ

Evolution.

It's inevitable. An eternal
verity.

Just when you think you've
got it knocked, and you're
resting on your laurels, some-
body comes along and makes
a dinosaur out of you.

Witness what happened to
the Centronics printer when
the Epson MX-80 came along
in 1981.

And now, witness what's
happening to the MX-80 as
the ProWriter cometh to be
the foremost printer of the
decade.
SPEED

MX-80: 80 cps, for 46 full lines
per minute throughput.
PROWRITER: 120 cps, for
63 full lines per minute
throughput.
GRAPHICS

MX-80: Block graphics standard,
fine for things like bar graphs.
PROWRITER: High-resolu-
tion graphics features, fine
for bar graphs, smooth curves,
thin lines, intricate details, etc.
PRINTING

MX-80: Dot matrix business
quality.

PROWRITER: Dot matrix
correspondence quality, with
incremental printing capability
standard.
FEED

MX-80: Tractor feed standard;
optional friction-feed kit for
about $75 extra.
PROWRITER: Both tractor
and friction feed standard.
INTERFACE
MX-80: Parallel interface
standard; optional serial
interface for about $75 extra.
PROWRITER; Available stan-
dard-either parallel interface
or parallel/serial interface.
WARRANTY

MX-80: 90 days, from Epson.
PROWRITER: One full year,
from Leading Edge.
PRICE
Heh, heh.

Marketed Exclusively by Leading
Edge Products. Inc.. 225 Turnpike
Street, Canton. Massachusetts
02021. Call: toll-free 1-800-343-6833;
or in Massachusetts call collect
1617)828-8150 Telex 951-624.

LEAMHG
EDGr

For a free poster of "Ace "
IProwriter's pilot I doing his thing,
please write us.

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